Use the template provided below, using the week 2 section for this assignment.

 Infant Mental Health and Cultural Competence – ZERO TO THREE 

Throughout this course, you will be creating a series of parent handouts focused on the various ages and stages of development. The second week of class has discussed genetic and environmental influences on development, prenatal development, and the newborn stage; therefore, this will be the focus of your Week 2 assignment. Continuing with the same template from your Week 1 Theory Parent Handout assignment, complete the slides for the Week 2 portion.

To prepare:

· Read Chapter 2: Genetic and Environment Foundations

· Review Chapter 3: Prenatal Development

· Review Chapter 4: Birth and the Newborn Baby

· Read 

Infant Mental Health and Cultural Competence

Links to an external site.

Find and open your latest version of the 
Parent Handout template on your computer. You will be adding on to this document.


For your assignment, complete the following:


· Describe two genetic factors that can influence prenatal development.

· Describe two environmental factors that can influence prenatal development.

· Discuss how you will use Bronfenbrenner’s ecological systems theory to support families during the prenatal and newborn stage.

· Explain three resources for families to support them during the prenatal and newborn stage of development. Be sure to include a link to each resource.

· One resource should be a quick read for families on the go.

· One resource should be more detailed for families who want to learn more.

· One resource should be user-friendly for diverse families (e.g., ELL, single parents, grandparents raising grandchildren, etc.).


· Explain the role of an educator in supporting the prenatal development of families in their care.

· Describe how the ideas you shared in the parent handout section of this assignment are supported by the theory you aligned with in your Week 1 Discussion: Child Development Theories.

· Discuss how an understanding of each family’s cultural context can make you a more effective educator during this time frame.


The Prenatal and Newborn Parent Handout assignment

· Must be three pages in length and formatted according to template.

· Must utilize academic voice. See the 

Academic Voice

 Links to an external site.
resource for additional guidance.

· Must use at least two scholarly sources in addition to the course text. These scholarly resources should be different than the resources provided for families. Must follow 

APA Style

 Links to an external site.
as outlined in the Writing Center.

· The 

Scholarly, Peer-Reviewed, and Other Credible Sources

 Links to an external site.
table offers additional guidance on appropriate source types. If you have questions about whether a specific source is appropriate for this assignment, please contact your instructor. Your instructor has the final say about the appropriateness of a specific source for a particular assignment.

· To assist you in completing the research required for this assignment, view the 

Quick and Easy Library Research

 Links to an external site.
tutorial, which introduces the University of Arizona Global Campus Library and the research process, and provides some library search tips.


Save Our Environment

F. N. Mithila, 12 years, Bangladesh

Children and adults enjoy themselves, embedded in the supportive context of an idyllic urban landscape. Chapter 2 considers how heredity and multiple layers of the surrounding environment jointly influence child development.

Reprinted with permission from The International Museum of Children’s Art, Oslo, Norway


2.1 Genetic Foundations

The Genetic Code • The Sex Cells • Sex Determination • Multiple Offspring • Patterns of Gene–Gene Interaction • Chromosomal Abnormalities

2.2 Reproductive Choices

Genetic Counseling • Prenatal Diagnosis • Adoption

■ Social Issues: health: The Pros and Cons of Reproductive Technologies

2.3 Environmental Contexts for Development

The Family • Socioeconomic Status and Family Functioning • Affluence • Poverty • Beyond the Family: Neighborhoods and Schools • The Cultural Context

■ Social Issues: education: Worldwide Education of Girls: Transforming Current and Future Generations

■ Cultural Influences: Familism Promotes Competence in Hispanic Children and Youths

2.4 Understanding the Relationship Between Heredity and Environment

The Question, “How Much?” • The Question, “How?”

■ Biology and Environment: The Tutsi Genocide and Epigenetic Transmission of Maternal Stress to Children

It’s a girl!” announces the doctor, holding up the squalling newborn baby as her parents gaze with amazement at their miraculous creation.

“A girl! We’ve named her Sarah!” exclaims the proud father to eager relatives waiting for news of their new family member.

As we join these parents in thinking about how this wondrous being came into existence and imagining her future, we are struck by many questions. How did this baby, equipped with everything necessary for life outside the womb, develop from the union of two tiny cells? What ensures that Sarah will, in due time, roll over, reach for objects, walk, talk, make friends, learn, imagine, and create—just like other typical children born before her? Why is she a girl and not a boy, dark-haired rather than blond, calm and patient rather than energetic and distractible? What difference will it make that Sarah is given a name and place in one family, community, nation, and culture rather than another?

To answer these questions, this chapter takes a close look at the foundations of development: heredity and environment. Because nature has prepared us for survival, all humans have features in common. Yet each of us is also unique. Think about several children you know well, and jot down the most obvious physical and behavioral similarities between them and their parents. Did you find that one child shows combined features of both parents, another resembles just one parent, whereas a third is not like either parent? These directly observable characteristics are called phenotypes. They depend in part on the individual’s genotype—the complex blend of genetic information that determines our species and influences all our unique characteristics. Yet phenotypes are also affected by each person’s lifelong history of experiences.

We begin our discussion with a review of basic genetic principles that help explain similarities and differences among children in appearance and behavior. Then we turn to aspects of the environment that play powerful roles in children’s lives. As our discussion proceeds, some findings may surprise you. For example, many people are convinced that when children inherit unfavorable characteristics, little can be done to help them. Others believe that the damage done to children by a harmful environment can easily be corrected. As we will see, neither of these assumptions is accurate. Rather, heredity and environment continuously collaborate, each modifying—for better or for worse—the power of the other to influence the course of development. ■


2.1a Explain what genes are and how they are transmitted from one generation to the next.

2.1b Describe various patterns of gene–gene interaction.

2.1c Describe major chromosomal abnormalities, and explain how they occur.

Within each of the trillions of cells in the human body (except red blood cells) is a control center, or nucleus, that contains rodlike structures called chromosomes, which store and transmit genetic information. Human chromosomes come in 23 matching pairs; an exception is the XY pair in males, which we will discuss shortly. Each member of a pair corresponds to the other in size, shape, and genetic functions. One chromosome is inherited from the mother and one from the father (see Figure 2.1 on page 52).

2.1.1 The Genetic Code

Chromosomes are made up of a chemical substance called deoxyribonucleic acid, or DNA. As Figure 2.2 on page 52 shows, DNA is a long, double-stranded molecule that looks like a twisted ladder. Each rung of the ladder consists of a specific pair of chemical substances called bases. It is this sequence of base pairs that provides genetic instructions. Although the bases always pair up in the same way across the ladder rungs—A with T and C with G—they can occur in any order along its sides. A gene is a segment of DNA along the length of the chromosome. Genes can be of different lengths—perhaps 100 to several thousand ladder rungs long. An estimated 19,000 to 20,000 protein-coding genes, which directly affect our body’s characteristics, lie along the human chromosomes (Ezkurdia et al., 2014). They send instructions for making a rich assortment of proteins to the cytoplasm, the area surrounding the cell nucleus. Proteins, which trigger chemical reactions throughout the body, are the biological foundation on which our characteristics are built. An additional 18,000 regulator genes modify the instructions given by protein-coding genes, greatly complicating their genetic impact (Pennisi, 2012).

Figure 2.1 A karyotype, or photograph, of human chromosomes. The 46 chromosomes shown on the left were isolated from a human cell, stained, greatly magnified, and arranged in pairs according to decreasing size of the upper “arm” of each chromosome. The twenty-third pair, XY, reveals that the cell donor is a genetic male. In a genetic female, this pair would be XX.


We share some of our DNA with even the simplest organisms, such as bacteria and molds, and most of it with other mammals, especially primates. About 99 percent of chimpanzee and human DNA is identical. And the genetic variation from one human to the next is even less: Individuals around the world are about 99.6 percent genetically identical (Tishkoff & Kidd, 2004; Wong, 2014). But these straightforward comparisons are misleading. Many human DNA segments that appear like those of chimpanzees have undergone duplications and rearrangements with other segments. So in actuality, the species-specific genetic material responsible for the attributes that make us human, from our upright gait to our extraordinary language and cognitive capacities, is extensive (Sudmant et al., 2015). Furthermore, it takes a change in only a single DNA base pair to influence human traits. And such tiny changes generally combine in unique ways across multiple genes, amplifying human variability.

Figure 2.2 DNA’s ladderlike structure. A gene is a segment of DNA along the length of the chromosome, varying from perhaps 100 to several thousand ladder rungs long. The pairings of bases across the rungs of the ladder are very specific: Adenine (A) always appears with thymine (T), and cytosine (C) always appears with guanine (G).

How do humans, with far fewer genes than scientists once thought, manage to develop into such complex beings? The answer lies in the proteins our genes make, which break up and reassemble in staggering variety—about 10 to 20 million altogether. Simpler species have far fewer proteins. Furthermore, the communication system between the cell nucleus and cytoplasm, which fine-tunes gene activity, is more intricate in humans than in simpler organisms. Finally, within the cell, environmental factors modify gene expression. Many such effects are unique to humans and influence brain development (Lussier, Islam, & Kobor, 2018). So even at this microscopic level, biological events of profound developmental significance are the result of both genetic and nongenetic forces.

2.1.2 The Sex Cells

New individuals are created when two special cells called gametes, or sex cells—the sperm and ovum—combine. A gamete contains only 23 chromosomes, half as many as a regular body cell. Gametes are formed through a cell division process called meiosis, which halves the number of chromosomes normally present in body cells. When sperm and ovum unite at conception, the resulting cell, called a zygote, will again have 46 chromosomes. Meiosis ensures that a constant quantity of genetic material is transmitted from one generation to the next.

In meiosis, the chromosomes pair up and exchange segments, so that genes from one are replaced by genes from another. This shuffling of genes creates new hereditary combinations. Then chance determines which member of each pair will gather with others and end up in the same gamete. These events make the likelihood that nontwin siblings will be genetically identical about 1 in 700 trillion, or virtually nil. The genetic variability produced by meiosis is adaptive: It increases the chances that at least some members of a species will cope with ever-changing environments and will survive.

In the male, the cells from which sperm arise are produced continuously throughout life, so a healthy man can father a child at any age after sexual maturity. The female is born with a bank of ova already present in her ovaries, though recent findings suggest that new ova may arise from ovarian stem cells later on (Virant-Klun, 2015). Still, there are plenty of female sex cells. About 1 to 2 million are present at birth, 40,000 remain at adolescence, and approximately 350 to 450 female sex cells will mature during a woman’s childbearing years (Moore, Persaud, & Torchia, 2016).

2.1.3 Sex Determination

Return to Figure 2.1 and note that 22 of the 23 pairs of chromosomes are matching pairs, called autosomes (meaning not sex chromosomes). The twenty-third pair consists of sex chromosomes. In females, this pair is called XX; in males, it is called XY. The X is a relatively long chromosome, whereas the Y is short and carries little genetic material. When gametes form in males, the X and Y chromosomes separate into different sperm cells. The gametes that form in females all carry an X chromosome. Therefore, the genetic sex of the new organism is determined by whether an X-bearing or a Y-bearing sperm fertilizes the ovum. In fact, scientists have isolated a gene on the Y chromosome that initiates the formation of male sex organs during the prenatal period (Sekido & Lovell-Badge, 2009). Additional genes, some yet to be identified, are involved in the development of sexual characteristics.

Biologists caution that human sexual diversity is much wider than a simple male–female dichotomy. As a result of variations in genes or chance events in development, some individuals’ sex chromosomes do not match their sexual anatomy. An estimated 1 in every 100 people are affected, usually mildly but occasionally substantially (Ainsworth, 2015). The existence of people with intersex traits, many of whom go through life unaware of their condition unless they seek treatment for infertility or another medical issue, is redefining sex as a spectrum.

2.1.4 Multiple Offspring

Ruth and Peter, a couple I know well, tried for several years to have a child, without success. Eventually, Ruth’s doctor prescribed a fertility drug, and twins—Jeannie and Jason—were born. Jeannie and Jason are fraternal, or dizygotic, twins, the most common type of multiple offspring, resulting from the release and fertilization of two ova. Genetically, they are no more alike than ordinary siblings. Table 2.1 on page 254 summarizes genetic and environmental factors that increase the chances of giving birth to fraternal twins. Older maternal age, fertility drugs, and in vitro fertilization are major causes of the dramatic rise in fraternal twinning and other multiple births in industrialized nations over the past several decades. Currently, fraternal twins account for 1 in about every 33 births in the United States (Martin et al., 2017).

Table 2.1 Maternal Factors Linked to Fraternal Twinning




Occurs more often among women whose families contain fraternal twins, suggesting a genetic influence. Two recently identified genes, one that augments hormone levels and another that may heighten the ovaries’ responsiveness to hormones, increase the chances of fraternal twinning.

Geographic region

Occurs in 6 per 1,000 births in Asia and Latin America, 9 to 12 per 1,000 births in White Europeans, and 40 per 1,000 births among Black Africansa


Rises with maternal age, peaking between 35 and 39 years, and then rapidly falls

Body build

Occurs more often among women who are tall and overweight or of normal weight as opposed to slight body build

Number of births

Is more likely with each additional birth

Fertility drugs and in vitro fertilization

Is more likely with fertility hormones and in vitro fertilization (see page 61), which also increase the chances of bearing higher-order multiples

a Worldwide rates, not including multiple births resulting from use of fertility drugs.

Sources: Hoekstra et al., 2008, 2010; Kulkarni et al., 2013; Smits & Monden, 2011; Mbarek et al., 2016.

Twins can also be created when a zygote that has started to duplicate separates into two clusters of cells that develop into two individuals. These are called identical, or monozygotic, twins because they have the same genetic makeup. The frequency of identical twins is the same around the world—about 3 to 4 per 1,000 births (Kulkarni et al., 2013). Animal research has uncovered environmental influences that prompt this type of twinning, including temperature changes, variation in oxygen levels, and late fertilization of the ovum (Lashley, 2007). In a minority of cases, identical twinning runs in families, but this occurs so rarely that it is likely due to chance rather than heredity.

During their early years, children of single births often are healthier and develop more rapidly than twins. Jeannie and Jason, like most twins, were born several weeks prematurely and required special care in the hospital. When the twins came home, Ruth and Peter had to divide time between them. Perhaps because neither baby received as much attention as the average single infant, Jeannie and Jason walked and talked several months later than most children their age, though like most twins they caught up in development by middle childhood (Lytton & Gallagher, 2002; Nan et al., 2013; Raz et al., 2016). Parental energies are further strained after the birth of triplets, whose early development is slower than that of twins (Feldman, Eidelman, & Rotenberg, 2004).

These identical, or monozygotic, twins were created when a duplicating zygote separated into two clusters of cells, which developed into two individuals with the same genetic makeup.


2.1.5 Patterns of Gene–Gene Interaction

Jeannie has her parents’ dark, straight hair; Jason is curly-haired and blond. The way genes from each parent interact helps explain these outcomes. Recall that except for the XY pair in males, all chromosomes come in matching pairs. Two forms of each gene occur at the same place on the chromosomes, one inherited from the mother and one from the father. Each form of a gene is called an allele. If the alleles from both parents are alike, the child is homozygous and will display the inherited trait. If the alleles differ, then the child is heterozygous, and relationships between the alleles influence the phenotype.

Dominant–Recessive Pattern

In many heterozygous pairings, dominant–recessive inheritance occurs: Only one allele affects the child’s characteristics. It is called dominant; the second allele, which has no effect, is called recessive. Hair color is an example. The allele for dark hair is dominant (we can represent it with a capital D), whereas the one for blond hair is recessive (symbolized by a lowercase b). Both a child who inherits a homozygous pair of dominant alleles (DD) and a child who inherits a heterozygous pair (Db) will be dark-haired, even though their genotypes differ. Blond hair (like Jason’s) can result only from having two recessive alleles (bb). Still, heterozygous individuals with just one recessive allele (Db) can pass that trait to their children. Therefore, they are called carriers of the trait.

Most recessive alleles—like those for blond hair, pattern baldness, or nearsightedness—are of little developmental importance. But some cause serious disabilities and diseases. One well-known recessive disorder is phenylketonuria, or PKU, which affects the way the body breaks down proteins contained in many foods. Infants born with two recessive alleles lack an enzyme that converts one of the basic amino acids that make up proteins (phenylalanine) into a byproduct essential for body functioning (tyrosine). Without this enzyme, phenylalanine quickly builds to toxic levels that damage the central nervous system, causing permanent intellectual disability.

Despite its potentially damaging effects, PKU illustrates that inheriting unfavorable genes does not always lead to an untreatable condition. All U.S. states require that each newborn be given a blood test for PKU. If the disease is found, doctors place the baby on a diet low in phenylalanine. Children who receive this treatment nevertheless show mild deficits in control of attention, memory, planning, decision making, and problem solving, because even small amounts of phenylalanine interfere with brain functioning (Fonnesbeck et al., 2013; Jahja et al. 2014). But as long as dietary treatment begins early and continues, children with PKU usually attain an average level of intelligence and have a normal lifespan.

In dominant–recessive inheritance, if we know the genetic makeup of the parents, we can predict the percentage of children in a family who are likely to display or carry a trait. Figure 2.3 illustrates this for PKU. For a child to inherit the condition, each parent must have a recessive allele. But because of the action of regulator genes, children vary in the degree to which phenylalanine accumulates in their tissues and in the extent to which they respond to treatment.


Figure 2.3 Dominant–recessive mode of inheritance, as illustrated by PKU. When both parents are heterozygous carriers of the recessive gene (p), we can predict that 25 percent of their offspring are likely to be normal (NN), 50 percent are likely to be carriers (Np), and 25 percent are likely to inherit the disorder (pp). Notice that the child with PKU, in contrast to his siblings, has light hair. The recessive gene for PKU affects more than one trait. It also leads to fair coloring.

Only rarely are serious diseases due to dominant alleles. Think about why this is so. Children who inherit the dominant allele always develop the disorder. They seldom live long enough to reproduce, so the harmful dominant allele is eliminated from the family’s heredity in a single generation. Some dominant disorders, however, do persist. One is Huntington disease, a condition in which the central nervous system degenerates. Its symptoms usually do not appear until age 35 or later, after the person may have passed the dominant allele to his or her children.

Incomplete-Dominance Pattern

In some heterozygous circumstances, the dominant–recessive relationship does not hold completely. Instead, we see incomplete dominance, a pattern of inheritance in which both alleles are expressed in the phenotype, resulting in a combined trait, or one that is intermediate between the two.

The sickle cell trait, a heterozygous condition present in many Black Africans, provides an example. Sickle cell anemia occurs in full form when a child inherits two recessive alleles. They cause the usually round red blood cells to become sickle (crescent-moon) shaped, especially under low-oxygen conditions. The sickled cells clog the blood vessels and block the flow of blood, causing intense pain, swelling, and tissue damage. Despite medical advances that today allow 85 percent of affected children to survive to adulthood, North Americans with sickle cell anemia have an average life expectancy of only 55 years (Chakravorty & Williams, 2015). Heterozygous individuals are protected from the disease under most circumstances. However, when they experience oxygen deprivation—for example, at high altitudes or after intense physical exercise—the single recessive allele asserts itself, and a temporary, mild form of the illness occurs.

The sickle cell allele is common among Black Africans for a special reason. Carriers of it are more resistant to malaria than are individuals with two alleles for normal red blood cells. In Africa, where malaria is common, these carriers survived and reproduced more frequently than others, leading the gene to be maintained in the Black population. But in regions of the world where the risk of malaria is low, the frequency of the gene is declining. For example, only 8 percent of African Americans are carriers, compared with 20 percent of Black Africans (Centers for Disease Control and Prevention, 2017h).

X-Linked Pattern

Males and females have an equal chance of inheriting recessive disorders carried on the autosomes. When a harmful allele is carried on the X chromosome, however, X-linked inheritance applies, making males more likely to be affected because their sex chromosomes do not match. In females, any recessive allele on one X chromosome has a good chance of being suppressed by a dominant allele on the other X. But the Y chromosome is only about one-third as long and therefore lacks many corresponding alleles to override those on the X.

A well-known example of X-linked inheritance is hemophilia, a disorder in which the blood fails to clot normally. Figure 2.4 shows its greater likelihood of inheritance by male children whose mothers carry the abnormal allele. Another example is fragile X syndrome, the most common inherited cause of intellectual disability. In this disorder, which affects about 1 in 2,000 males and 1 in 6,000 females, an abnormal repetition of a sequence of DNA bases occurs on the X chromosome, damaging a particular gene. In addition to cognitive impairments, the majority of individuals with fragile X syndrome suffer from attention deficits and high anxiety, and about 30 to 35 percent also have symptoms of autism (Wadell, Hagerman, & Hessl, 2013). Because the disorder is X-linked, males are more often affected.

Besides X-linked disorders, many sex differences reveal the male to be at a disadvantage. Rates of miscarriage, infant and childhood deaths, birth defects, learning disabilities, behavior disorders, and intellectual disability all are higher for boys (Boyle et al., 2011; MacDorman & Gregory, 2015). It is possible that these sex differences can be traced to the genetic code. The female, with two X chromosomes, benefits from a greater variety of genes. Nature, however, seems to have adjusted for the male’s disadvantage. Worldwide, about 103 boys are born for every 100 girls, and an even greater number of males are conceived (United Nations, 2017).

In cultures with strong gender-biased attitudes that induce expectant parents to prefer a male child, the male-to-female birth sex ratio is often much larger. In China, for example, the spread of ultrasound technology (which enables prenatal sex determination) and enforcement of a one-child family policy to control population growth—both of which began in the 1980s—led to a dramatic increase in sex-selective abortion. In 2015, China ended its one-child policy, substituting a two-child policy. Nevertheless, many Chinese couples continue to say they desire just one child (Basten & Jiang, 2015; Jiang, Li, & Sanchez-Barricarte, 2016). Today, China’s birth sex ratio is 117 boys for every 100 girls—a gender imbalance with adverse social consequences, such as rising crime rates and male competition for marriage partners.

Figure 2.4 X-linked inheritance. In the example shown here, the allele on the father’s X chromosome is normal. The mother has one normal and one abnormal recessive allele on her X chromosomes. By looking at the possible combinations of the parents’ alleles, we can predict that 50 percent of these parents’ male children are likely to have the disorder and 50 percent of their female children are likely to be carriers of it.

In contrast, in Europe, the Middle East, and North America, the proportion of male births has declined in recent decades. Some researchers attribute this trend to a rise in stressful living conditions, which heighten spontaneous abortions, especially of male fetuses (Catalano et al., 2010). In support of this hypothesis, dips in the male-to-female birth ratio have been documented after armed conflicts, environmental disasters, and financial crises, such as the economic recession of 2007–2009 (Catalano et al., 2009; Grech, 2014).

In sum, social and cultural factors can modify the male-to-female birth sex ratio, in either direction. And they can readily undermine the ratio’s assumed evolutionary role: compensating for males’ greater genetic vulnerability.

Genomic Imprinting

More than 1,000 human characteristics follow the rules of dominant–recessive and incomplete-dominance inheritance (McKusick-Nathans Institute of Genetic Medicine, 2018). For these traits, whichever parent contributes a gene to the new individual, the gene responds similarly. Geneticists, however, have identified some exceptions. In genomic imprinting, alleles are imprinted, or chemically marked, within the ovum or sperm in such a way that one pair member (either the mother’s or the father’s) is silenced, leaving the other to be expressed regardless of its makeup (Perez, Rubinstein, & Dulac, 2016). The imprint may be passed to the next generation or be temporary, erased in the next generation.

A 9-year-old who has fragile X syndrome participates in an art class with typical students. This disorder—the most common inherited cause of intellectual disability—results from an abnormal repetition of a sequence of DNA bases that damages a gene on the X chromosome.


The number of genes subjected to genomic imprinting is believed to be small—less than 1 percent. Nevertheless, these genes have a significant impact on brain development and physical health, as disruptions in imprinting reveal. For example, imprinting is involved in several childhood cancers and in Prader-Willi syndrome, a rare disorder with symptoms of intellectual disability, delays in language motor development, small stature, and severe obesity (Zoghbi & Beaudet, 2016). Imprinting also may explain why children are more likely to develop diabetes if their father, rather than their mother, suffers from it, and why people with asthma or hay fever tend to have mothers, not fathers, with the illness (Ishida & Moore, 2013).


Although less than 3 percent of pregnancies result in the birth of a baby with a hereditary abnormality, these children account for about 20 percent of infant deaths and contribute substantially to lifelong impaired physical and mental functioning (Martin et al., 2017). How are harmful genes created in the first place? The answer is mutation, a sudden but permanent change in a segment of DNA. A mutation may affect only one or two genes, or it may involve many genes, as in the chromosomal disorders we will discuss shortly. Some mutations occur spontaneously, simply by chance. Others are caused by hazardous environmental agents.

Ionizing (high-energy) radiation is an established cause of mutation. Women who receive repeated doses before conception are more likely to miscarry or give birth to children with hereditary defects. The incidence of genetic abnormalities, such as physical malformations and childhood cancer, is also higher in children whose fathers are exposed to radiation in their occupations. However, infrequent and mild exposure to radiation generally does not cause genetic damage (Adelstein, 2014). Rather, moderate to high doses over an extended time can impair DNA.

The examples just given illustrate germline mutation, which takes place in the cells that give rise to gametes. When the affected individual mates, the defective DNA is passed on to the next generation. In a second type, called somatic mutation, normal body cells mutate, an event that can occur at any time of life. The DNA defect appears in every cell derived from the affected body cell, eventually causing disease (such as cancer) or disability.

It is easy to see how disorders that run in families can result from germline mutation. But somatic mutation may be involved in these disorders as well. Some people harbor a genetic susceptibility that causes certain body cells to mutate easily in the presence of triggering events (Insel, 2014). This helps explain why certain individuals develop serious illnesses (such as cancer) as a result of smoking, exposure to pollutants, or psychological stress, while others do not.

Although virtually all mutations that have been studied are harmful, some spontaneous ones (such as the sickle cell allele in malaria-ridden regions of the world) are necessary and desirable. By increasing genetic variation, they help individuals adapt to unexpected environmental challenges. Scientists, however, seldom go looking for mutations that contribute to favorable traits, such as an exceptional talent or sturdy immune system. They are far more concerned with identifying and eliminating unfavorable genes that threaten health and survival.

Polygenic Inheritance

So far, we have discussed patterns of gene–gene interaction in which people either display a particular trait or do not. These cut-and-dried individual differences are much easier to trace to their genetic origins than are characteristics that vary on a continuum among people, such as height, weight, intelligence, and personality. These traits are due to polygenic inheritance, in which many genes affect the characteristic in question. Polygenic inheritance is complex, and much about it is still unknown. In the final section of this chapter, we will discuss how researchers infer the influence of heredity on human attributes when they do not know the precise patterns of inheritance.

2.1.6 Chromosomal Abnormalities

Besides harmful recessive alleles, abnormalities of the chromosomes are a major cause of serious developmental problems. Most chromosomal defects result from mistakes during meiosis, when the ovum and sperm are formed. A chromosome pair does not separate properly, or part of a chromosome breaks off. Because these errors involve far more DNA than problems due to single genes, they usually produce many physical and mental symptoms.

Down Syndrome

The most common chromosomal disorder, occurring in 1 out of every 700 live births, is Down syndrome. In 95 percent of cases, it results from a failure of the twenty-first pair of chromosomes to separate during meiosis, so the new individual receives three of these chromosomes rather than the normal two. For this reason, Down syndrome is sometimes called trisomy 21. In other, less frequent forms, an extra broken piece of a twenty-first chromosome is attached to another chromosome (called translocation pattern). Or an error occurs during early prenatal cell duplication, causing some but not all body cells to have the defective chromosomal makeup (called mosaic pattern) (U.S. Department of Health and Human Services, 2017). Because the mosaic type involves less genetic material, symptoms may be less extreme.

The consequences of Down syndrome include intellectual disability, memory and speech problems, limited vocabulary, and slow motor development. EEG measures of brain activity reveal substantial disruption in connectivity among brain regions. This indicates that the brains of individuals with Down syndrome function in a less coordinated fashion than the brains of typical individuals (Ahmadlou et al., 2013). The disorder is also associated with distinct physical features—a short, stocky build, a flattened face, a protruding tongue, almond-shaped eyes, and (in 50 percent of cases) an unusual crease running across the palm of the hand. In addition, infants with Down syndrome are often born with eye cataracts, hearing loss, and heart and intestinal defects (U.S. Department of Health and Human Services, 2017).

Because of medical advances, life expectancy of individuals with Down syndrome has increased greatly: Today, it is about 60 years. However, about 70 percent of affected people who live past age 40 show symptoms of Alzheimer’s disease, the most common form of dementia (Hartley et al., 2015). Genes on chromosome 21 are linked to this disorder.

An 8-year-old with Down syndrome, at right, plays with a typically developing classmate. Despite impaired intellectual development, this child benefits from exposure to stimulating environments and from opportunities to interact with peers.


Infants with Down syndrome smile less readily, show poor eye-to-eye contact, have weak muscle tone, and explore objects less persistently (Slonims & McConachie, 2006). But when parents encourage them to engage with their surroundings, children with Down syndrome develop more favorably. They also benefit from infant and preschool intervention programs, although emotional, social, and motor skills improve more than intellectual performance (Roizen, 2013). Clearly, environmental factors affect how well children with Down syndrome fare.

As Figure 2.5 shows, the risk of bearing a baby with Down syndrome, as well as other chromosomal abnormalities, rises dramatically with maternal age. Chromosomal analyses of ova from older women reveal errors during meiosis in the pairing up of chromosomes and exchange of segments between the pairs (Herbert et al., 2015). In about 5 percent of cases, the extra genetic material originates with the father (Vranekovic et al., 2012).

Abnormalities of the Sex Chromosomes

Other disorders of the autosomes usually disrupt development so severely that miscarriage occurs. When such babies are born, they rarely survive beyond early childhood. In contrast, sex chromosome disorders often are not recognized until adolescence when, in some deviations, puberty is delayed. The most common problems involve the presence of an extra chromosome (either X or Y) or the absence of one X in females.

Figure 2.5 Risk of Down syndrome and all chromosomal abnormalities by maternal age. Risk rises sharply after age 35. (From Batshaw, M. L., Roizen, N. J., & Pellegrino, L. (2012) Children with Disabilities, Seventh Edition. (p. 433): Reprinted with permission of Paul H. Brookes Publishing Co., Inc. Batshaw, M. L., Roizen, N. J., & Pellegrino, L. (2019) Children with Disabilities, Eighth Edition, available at

Research has discredited a variety of myths about individuals with sex chromosome disorders. For example, males with XYY syndrome are not necessarily more aggressive and antisocial than XY males (Re & Birkhoff, 2015). And most children with sex chromosome disorders do not suffer from intellectual disability but, rather, have specific cognitive challenges. Verbal difficulties—for example, with reading and vocabulary—are common among girls with triple X syndrome and boys with Klinefelter syndrome, both of whom inherit an extra X chromosome. In contrast, girls with Turner syndrome, who are missing an X, have trouble with spatial relationships—for example, drawing pictures, following travel directions, and noticing changes in facial expressions (Otter et al., 2013; Ross et al., 2012; Temple & Shephard, 2012). Brain-imaging evidence confirms that adding to or subtracting from the usual number of X chromosomes alters the development of certain brain structures, yielding particular intellectual deficits (Hong et al., 2014).

Ask Yourself

Connect ■ Referring to ecological systems theory (Chapter 1, pages 25–27), explain why parents of children with genetic disorders often experience increased stress. What factors, within and beyond the family, can help these parents support their children’s development?

Apply ■ Gilbert’s genetic makeup is homozygous for dark hair. Jan’s is homozygous for blond hair. What proportion of their children are likely to be dark-haired? Explain.

Reflect ■ Provide illustrations from our discussion, and from individuals you know with genetic disorders, of environmental influences on development.


2.2 Discuss counseling, medical procedures, and reproductive options that can assist prospective parents in having healthy children.

In the past, many couples with genetic disorders in their families chose not to bear a child at all rather than risk the birth of a baby with abnormalities. Today, genetic counseling and prenatal diagnosis help people make informed decisions about conceiving, carrying a pregnancy to term, or adopting a child.

Social Issues: HealthThe Pros and Cons of Reproductive Technologies

Some people decide not to risk pregnancy because of a history of genetic disease. Many others—12 percent of all couples who try to conceive—discover that they are infertile (Centers for Disease Control and Prevention, 2016). And some never-married adults and lesbian and gay couples want to bear children. Today, increasing numbers of individuals are turning to alternative methods of conception—technologies that have become the subject of heated debate.

Donor Insemination and In Vitro Fertilization

Donor insemination—injection of sperm from an anonymous man into a woman—is often used to overcome male reproductive difficulties. It also permits women without a male partner to become pregnant. Donor insemination is 70 percent successful, resulting in about 40,000 deliveries and 52,000 newborn babies in the United States each year (Rossi, 2014).

In vitro fertilization is another commonly used reproductive technology. About 1 percent of all children in developed countries—65,000 babies in the United States—are conceived through this technique annually (Sunderam et al., 2015). A woman is given hormones that stimulate ripening of several ova. These are removed surgically and placed in a dish of nutrients, to which sperm are added. Once an ovum is fertilized and duplicates into several cells, it is injected into the woman’s uterus.

By mixing and matching gametes, pregnancies can be brought about when either or both partners have a reproductive problem. Usually, in vitro fertilization is used to treat women whose fallopian tubes are permanently damaged. But a single sperm can now be injected directly into an ovum, thereby overcoming most male fertility problems. And a “sex sorter” method helps ensure that couples who carry X-linked diseases (which usually affect males) have a daughter.

Nevertheless, the success of assisted reproduction declines steadily with age, from 55 percent in women ages 31 to 35 to 8 percent in women age 43 (Cetinkaya, Siano, & Benadiva, 2013; Gnoth et al., 2011). Furthermore, assisted reproduction is associated with an elevated risk of pregnancy complications, miscarriage, and birth defects, due to the biological effects of in vitro techniques and the older age of many people seeking treatment.

Children conceived through these methods may be genetically unrelated to one or both of their parents. Does lack of genetic ties or secrecy interfere with parent–child relationships? Perhaps because of a strong desire for parenthood, caregiving is actually somewhat warmer for young children conceived through donor insemination or in vitro fertilization. Also, these children and adolescents are as well-adjusted as their naturally conceived counterparts (Punamaki, 2006; Wagenaar et al., 2011). Children whose parents feel comfortable telling them about their gamete-donor origins are particularly advantaged in parent–child relationship quality and psychological well-being. Telling children early, by age 7, appears most beneficial (Ilioi et al., 2017; Rueter et al., 2016). Perhaps older children’s more complex appreciation of the meaning of being genetically unrelated to at least one parent leads them to be less accepting.

Although reproductive technologies have many benefits, serious questions have arisen about their use. In many countries, including the United States, doctors are not required to keep records of donor characteristics, though information about the child’s genetic background might be critical in the case of serious disease (Murphy, 2013). Another concern is that the in vitro “sex sorter” method enables parental sex selection, thereby eroding the moral value that boys and girls are equally precious.

In vitro fertilization poses greater risks than natural conception to infant survival and healthy development. About 26 percent of in vitro procedures result in multiple births. Most are twins, but 3 percent are triplets and higher-order multiples. Consequently, among in vitro babies, the rate of low birth weight is nearly four times as high as in the general population. In response, doctors have reduced the number of fertilized ova injected into a woman’s uterus, typically to no more than two (Kulkarni et al., 2013; Sunderam et al., 2015). Risk of pregnancy complications, miscarriage, and major birth defects also rises, due to the biological effects of in vitro techniques and the older age of many people seeking treatment.

Surrogate Motherhood

An even more controversial form of medically assisted conception is surrogate motherhood. In this procedure, in vitro fertilization may be used to impregnate a woman (called a surrogate) with a couple’s fertilized ovum. Alternatively, sperm from a man whose partner is infertile may be used to inseminate the surrogate, who agrees to turn the baby over to the father. The child is then adopted by his partner. In both cases, the surrogate is paid a fee for her childbearing services.

Most surrogate arrangements proceed smoothly, and the limited evidence available suggests that families usually function well and stay in touch with the surrogate, especially if she is genetically related to the child (Golombok et al., 2011, 2013; Jadva, Casey, & Golombok, 2012). The small number of children who have been studied are generally well-adjusted. Nevertheless, because surrogacy typically involves the wealthy as contractors for infants and the less economically advantaged as surrogates, it may promote exploitation of financially needy women (Frankford, Bennington, & Ryan, 2015).

Reproductive Frontiers

Experts are debating the ethics of other reproductive options. Doctors have used donor ova from younger women in combination with in vitro fertilization to help postmenopausal women become pregnant. Most recipients are in their forties, but some in their fifties and sixties, and a few in their early seventies, have given birth. These cases magnify health risks to mother and baby and bring children into the world whose parents may not live to see them reach adulthood.

Today, customers at donor banks can select ova or sperm on the basis of physical characteristics and even IQ. And scientists are devising ways to alter the DNA of human ova, sperm, and embryos to protect against hereditary disorders—techniques that could be used to engineer other desired characteristics. Many worry that these practices are dangerous steps toward “designer babies”—controlling offspring traits by manipulating genetic makeup.

Although reproductive technologies permit many barren adults to become parents, laws are needed to regulate such practices. In Australia, New Zealand, and Europe, in vitro gamete donors and applicants for the procedure must undergo highly regulated screening. Denmark, France, and Italy prohibit in vitro fertilization for women past menopause (Cutas & Smajdor, 2015; Murphy, 2013). Pressure from those working in the field of assisted reproduction may lead to similar policies in the United States.

The ethical problems of surrogate motherhood are so complex that 18 U.S. states and the District of Columbia sharply restrict or ban the practice. Most European nations, along with Australia and Canada, allow only “altruistic” surrogacy, in which the surrogate has no financial gain. More research on how such children grow up, including later-appearing medical conditions and feelings about their origins, is important for weighing the pros and cons of these techniques.

2.2.1 Genetic Counseling

Genetic counseling is a communication process designed to help couples assess their chances of giving birth to a baby with a hereditary disorder and choose the best course of action in view of risks and family goals. Individuals likely to seek counseling are those who have had difficulties bearing children—for example, repeated miscarriages—or who know that genetic problems exist in their families.

In addition, adults who delay childbearing are often candidates because as maternal age rises beyond age 35, the rates of chromosomal abnormalities increase sharply. Older paternal age elevates risk of DNA mutations as well. After age 40, it is associated with increased incidence of several serious psychological disorders. These include autism (see page 23 in Chapter 1); schizophrenia, characterized by hallucinations, delusions, and irrational behavior; and bipolar disorder, marked by alternating periods of elation and depression (Zitzmann, 2013). But because younger parents have children in far higher numbers than older parents, they still bear the majority of babies with genetic defects. Therefore, some experts argue that parental needs, not age, should determine referral for genetic counseling (Berkowitz, Roberts, & Minkoff, 2006).

If prospective parents have a family history of intellectual disability, psychological disorders, physical defects, or inherited diseases, the genetic counselor interviews them and prepares a pedigree, a picture of the family tree in which affected relatives are identified. The pedigree is used to estimate the likelihood that a child will be affected by a disorder. For many disorders traceable to a single gene, molecular genetic testing using a sample of blood, saliva, or body tissue can reveal whether the parent is a carrier of the harmful allele.

Autism, schizophrenia, and bipolar disorder have each been linked to an array of DNA-sequence deviations (called genetic markers) distributed across multiple chromosomes. New genomewide testing methods, which look for these genetic markers, enable genetic counselors to estimate risk for these conditions and other psychological disorders. But estimates are generally low because the genetic markers are found in only a minority of affected people. Also, the genetic markers are not associated with mental illness every time they appear. Their expression—as we will illustrate at the end of this chapter—may depend on environmental conditions. Recently, geneticists have begun to identify rare repeats and deletions of DNA bases that are more consistently related to mental illness (Vissers, Gilissen, & Veltman, 2016). These discoveries may lead to more accurate prediction of the likelihood of passing a psychological disorder from parent to child.

When all the relevant hereditary information is in, genetic counselors help people consider appropriate options. These include taking a chance and conceiving or choosing from among a variety of reproductive technologies (see the Social Issues: Health box starting on page 60).

2.2.2 Prenatal Diagnosis

Several prenatal diagnostic methods—medical procedures that permit detection of developmental problems before birth—are available to couples at risk of bearing a child with abnormalities who decide to conceive (see Table 2.2). Women of advanced maternal age are prime candidates for amniocentesis or chorionic villus sampling. Ultrasound, commonly used during pregnancy to track fetal growth, permits detection of gross structural abnormalities. When ultrasound suggests problems but diagnosis is uncertain, ultrafast fetal magnetic resonance imaging, in which a scanner magnetically records detailed pictures of fetal structures, can be used for greater accuracy (see Figure 2.6). Except for maternal blood analysis, prenatal diagnostic methods should not be used routinely because of injury risks to the developing organism.

Prenatal diagnosis has led to advances in fetal medicine. For example, by inserting a needle into the uterus, doctors can administer drugs to the fetus. Surgery has been performed to repair such problems as heart, lung, and diaphragm malformations, urinary tract obstructions, and neural defects (Nassr et al., 2018). Fetuses with blood disorders have been given blood transfusions. And those with immune deficiencies have received bone marrow transplants that succeeded in creating a normally functioning immune system (Deprest et al., 2010).

Figure 2.6 Ultrafast MRI of a fetus, showing body structures. Ultrafast MRI is increasingly being used as a supplement to ultrasound because it records detailed pictures of body structures, permitting greater diagnostic accuracy. In this colorized MRI of a 26-week-old fetus, the yellow area highlights a brain abnormality.


These techniques frequently result in complications, the most common being premature labor and miscarriage (Danzer & Johnson, 2014). Yet parents may be willing to try almost any option, even one with only a slim chance of success. Currently, the medical profession is struggling with how to help parents make informed decisions about fetal surgery.

Table 2.2 Prenatal Diagnostic Methods




The most widely used technique. A hollow needle is inserted through the abdominal wall to obtain a sample of fluid in the uterus. Cells are examined for genetic defects. Can be performed by the 14th week after conception; 1 to 2 more weeks are required for test results. Small risk of miscarriage.

Chorionic villus sampling

A procedure that can be used if results are desired or needed very early in pregnancy. A thin tube is inserted into the uterus through the vagina, or a hollow needle is inserted through the abdominal wall. A small plug of tissue is removed from the end of one or more chorionic villi, the hairlike projections on the membrane surrounding the developing organism. Cells are examined for genetic defects. Can be performed at 9 weeks after conception; results are available within 24 hours. Entails a slightly greater risk of miscarriage than amniocentesis and is also associated with a small risk of limb deformities.


A small tube with a light source at one end is inserted into the uterus to inspect the fetus for defects of the limbs and face. Also allows a sample of fetal blood to be obtained, permitting diagnosis of such disorders as hemophilia and sickle cell anemia, as well as neural defects (see below). Usually performed between 15 and 18 weeks after conception but can be done as early as 5 weeks. Entails some risk of miscarriage.

Maternal blood analysis

By the second month of pregnancy, some of the developing organism’s cells enter the maternal bloodstream. An elevated level of alpha-fetoprotein may indicate kidney disease, abnormal closure of the esophagus, or neural tube defects, such as anencephaly (absence of most of the brain) and spina bifida (bulging of the spinal cord from the spinal column). Isolated cells can be examined for genetic defects.


High-frequency sound waves are beamed at the uterus; their reflection is translated into a picture on a video screen that reveals the size, shape, and placement of the fetus. By itself, permits assessment of fetal age, detection of multiple pregnancies, and identification of gross physical defects. Also used to guide amniocentesis, chorionic villus sampling, and fetoscopy. When used five or more times, may increase the chances of low birth weight.

Ultrafast magnetic resonance imaging (MRI)

Sometimes used as a supplement to ultrasound, where brain or other abnormalities are detected and MRI can provide greater diagnostic accuracy. Uses a scanner to magnetically record detailed pictures of fetal structures. The ultrafast technique overcomes image blurring due to fetal movements. No evidence of adverse effects.

Preimplantation genetic diagnosis

After in vitro fertilization and duplication of the zygote into a cluster of cells, one or two cells are removed and examined for genetic defects. Only if that sample is normal is the fertilized ovum implanted in the woman’s uterus.

Sources: Akolekar et al., 2015; Griffin et al., 2017; Jokhi & Whitby, 2011; Kollmann et al., 2013; Moore, Persaud, & Torchia, 2016.

Applying What We Know

Steps Prospective Parents Can Take Before Conception to Increase the Chances of a Healthy Baby



Arrange for a physical exam.

A physical exam before conception permits getting up to date on vaccinations and detection of diseases and other medical conditions that might reduce fertility, be difficult to treat during pregnancy, or affect the developing organism.

Consider your genetic makeup.

Find out if anyone in your family has had a child with a genetic disease or disability. If so, seek genetic counseling before conception.

Reduce or eliminate toxins under your control.

Because the developing organism is highly sensitive to damaging environmental agents during the early weeks of pregnancy, couples trying to conceive should avoid drugs, alcohol, cigarette smoke, radiation, pollution, chemical substances in the home and workplace, and exposure to infectious diseases. They should also stay away from ionizing radiation, which poses risks for mutations.

Ensure proper nutrition.

A doctor-recommended vitamin–mineral supplement, begun before conception, helps prevent many prenatal problems. It should include folic acid, which reduces the chances of neural tube defects, prematurity, and low birth weight (see Chapter 3, page 00).

Consult your doctor after 12 months of unsuccessful efforts at conception.

Long periods of infertility may be due to undiagnosed spontaneous abortions, which can be caused by genetic defects in either partner. If a physical exam reveals a healthy reproductive system, seek genetic counseling.

Advances in genetic engineering also offer hope for correcting hereditary defects. As part of the Human Genome Project—an ambitious international research program, extending from 1990 to 2003, that identified the sequence of DNA bases in the human genome—thousands of genes have been identified, including those involved in disorders of the heart, blood, eyes, lungs, digestive and nervous systems, and in many forms of cancer (National Institutes of Health, 2018b). As a result, new treatments are being explored.

One such approach is gene therapy—correcting genetic abnormalities by delivering DNA carrying a functional gene to the cells. Testing of gene therapies for treating severe immune system dysfunction, several forms of cancer, and certain blood disorders has been encouraging (Kaufmann et al., 2013). In a recent breakthrough, researchers successfully replaced an abnormal gene with a normal one in the red blood cells of young children with beta thalassemia, a disease in which low levels of hemoglobin cause life-threatening anemia and widespread organ damage (Thompson et al., 2018). In another approach, called proteomics, that shows special promise for treating heart disease and cancer, scientists modify genespecified proteins involved in particular diseases (Lippolis & De Angelis, 2016).

A 9-year-old with cystic fibrosis undergoes a breathing test to assess lung functioning. This recessive disorder causes the lungs, liver, and pancreas to secrete large amounts of thick mucus, leading to breathing and digestive difficulties. Worsening lung disease causes premature death in early adulthood. Today, researchers are testing gene therapies aimed at regenerating the lining of the lungs.


Despite some successes, genetic treatments are still some distance away for most single-gene defects and farther off for diseases involving multiple genes that combine in complex ways with each other and the environment. Applying What We Know above summarizes steps that prospective parents can take before conception to protect the genetic health of their child.

2.2.3 Adoption

Adults who are infertile or likely to pass along a genetic disorder, same-sex couples, and single adults who want a family are turning to adoption in increasing numbers. Couples who have children by birth, too, sometimes choose to expand their families through adoption. Because the availability of healthy babies has diminished (fewer young unwed mothers give up their babies than in the past), Americans, and people in other Western nations, often seek to adopt internationally. But despite a dramatic rise in orphaned, abandoned, and voluntarily surrendered children worldwide, intercountry adoption has declined substantially, due to host-country and U.S. adoption policies. Rising numbers of children are being adopted from U.S. foster care (Jones & Placek, 2017). And more families are accepting children who are past infancy or who have known developmental problems.

Adopted children and adolescents—whether or not born in their adoptive parents’ country—tend to have more learning and emotional difficulties than other children, a difference that increases with the child’s age at time of adoption (Askeland et al., 2017; Diamond et al., 2015; van den Dries et al., 2009). Various explanations exist for adoptees’ more problematic childhoods. The biological mother may have been unable to care for the child because of problems believed to be partly genetic, such as alcoholism or severe depression, and may have passed this tendency to her offspring. Or perhaps she experienced stress, poor diet, or inadequate medical care during pregnancy—factors that can affect the child. Furthermore, children adopted after infancy often have a preadoptive history of conflict-ridden family relationships, lack of parental affection, neglect and abuse, or deprived institutional rearing. Finally, adoptive parents and children, who are genetically unrelated, are less alike in intelligence and personality than are biological relatives—differences that may threaten family harmony.

Adoption is one option for adults who want a family but are infertile or have a family history of genetic disorders. This father and his 15-month-old daughter attend a reunion of families who traveled together to adopt babies from China. As she gets older, parental warmth and openness about her adoption will promote this child’s adjustment.

© Shari Lewis/AP Images

Despite these risks, most adopted children fare well, and those with preexisting problems who experience sensitive parenting usually make rapid progress (Arcus & Chambers, 2008; Juffer & van IJzendoorn, 2012). Overall, international adoptees develop much more favorably than birth siblings or institutionalized agemates who remain in their birth country (Christoffersen, 2012). And children with troubled family histories who are adopted at older ages generally improve in feelings of trust and affection for their adoptive parents as they come to feel loved and supported (Veríssimo & Salvaterra, 2006). As we will see in Chapter 5, however, later-adopted children—especially those with multiple early-life adversities—are more likely than their agemates to have persistent cognitive, emotional, and social problems.

By adolescence, adoptees’ lives are often complicated by unresolved curiosity about their roots. As they try to integrate aspects of their birth family and their adoptive family into their emerging identity, teenagers face a challenging process of defining themselves. When parents have been warm, open, and supportive in their communication about adoption, their children typically forge a positive sense of self and display fewer emotional and behavior problems (Brodzinsky, 2011; LeMare & Audet, 2014). Also, as long as parents took steps to help them learn about their birth heritage in childhood, young people adopted into a different ethnic group or culture generally develop identities that are healthy blends of their birth and rearing backgrounds (Barn, 2013; Thomas & Tessler, 2007). At the same time, intercountry adoptees who express a strong host-culture identity also tend to be well adjusted (Boivin & Hassan, 2015). If parents do not know enough about their child’s birth heritage to transmit it, adoptees may explore it later, in adulthood.

Ask Yourself

Connect ■ Why is genetic counseling called a communication process? Who should seek it, and why?

Apply ■ Imagine that you must counsel a couple considering in vitro fertilization using donor ova to overcome infertility. What medical and ethical risks would you raise?

Reflect ■ Suppose you are a carrier of fragile X syndrome and want to have children. Would you choose pregnancy, adoption, or surrogacy? If you became pregnant, would you opt for prenatal diagnosis? Explain your decisions.


2.3 Discuss aspects of children’s multi-layered environment that influence their development and well-being.

Just as complex as genetic inheritance is the surrounding environment—a multi-layered set of influences that combine to help or hinder physical and psychological well-being. Jot down a brief description of events and people that have significantly influenced your development. Do the items on your list resemble those of my students, who mostly mention experiences that involve their families? This emphasis is not surprising, since the family is the first and longest-lasting context for development. Other influences that make most students’ top ten are friends, neighbors, school, and community and religious organizations.

Return to Bronfenbrenner’s ecological systems theory, discussed in Chapter 1. It emphasizes that environments extending beyond the microsystem—the immediate settings just mentioned—also powerfully affect development. Indeed, my students rarely mention one important context. Its impact is so pervasive that we seldom stop to think about it in our daily lives. This is the macrosystem, or broad social climate of society—its values and programs that support and protect children’s development. All families need help in rearing children—through affordable housing and health care, safe neighborhoods, good schools, well-equipped recreational facilities, and high-quality child care and other services that permit them to meet both work and family responsibilities. And some families, because of poverty or special tragedies, need considerably more help than others.

In the following sections, we take up these contexts for development. Because they affect every age and aspect of change, we will return to them in later chapters. For now, our discussion emphasizes that environments, as well as heredity, can enhance or create risks for development.

2.3.1 The Family

In power and breadth of influence, no other microsystem context equals the family. The family creates unique bonds among people. Attachments to parents and siblings are usually lifelong and serve as models for relationships in the wider world. Within the family, children learn the language, skills, and social and moral values of their culture. Furthermore, research conducted in over 20 countries across six continents with tens of thousands of children and adults reveals that warm, affectionate family ties, especially with parents, consistently predict physical and psychological health throughout development (Khaleque & Rohner, 2012). In contrast, parental rejection—coldness, hostility, or indifference—is generally associated with developmental problems.

Contemporary researchers view the family as a network of interdependent relationships (Bronfenbrenner & Morris, 2006; Russell, 2014). Recall from ecological systems theory that family members exert bidirectional influences on one another, the behaviors of each affecting those of others. Indeed, the very term system implies that the responses of family members are related. These system influences operate both directly and indirectly.

Direct Influences

The next time you have a chance to observe family members interacting, watch carefully. You are likely to see that kind, patient communication evokes cooperative, harmonious responses, whereas harshness and impatience engender angry, resistive behavior. Each of these reactions, in turn, forges a new link in the interactive chain. In the first instance, a positive message tends to follow; in the second, a negative or avoidant one is likely.

This family is a network of interdependent relationships, in which each person’s behavior influences that of the others. As parents and children play a game, warm, considerate parental communication encourages children’s cooperation, which promotes further parental warmth and caring.


These observations fit with a wealth of research on the family system. Studies of families of diverse ethnicities show that when parents are firm but warm, children tend to comply with their requests. And when children cooperate, their parents are likely to be warm and gentle in the future. In contrast, children whose parents discipline harshly and impatiently are likely to refuse and rebel. And because children’s misbehavior is stressful, parents may increase their use of punishment, leading to more unruliness by the child (Lorber & Egeland, 2011; Shaw, Hyde, & Brennan, 2012). In each case, the behavior of one family member helps sustain a form of interaction in the other that either promotes or undermines children’s psychological well-being.

Indirect Influences

The impact of family relationships on development becomes even more complicated when we consider that interaction between any two members is affected by others present in the setting. Recall from Chapter 1 that Bronfenbrenner called these indirect influences the effect of third parties.

Look and Listen

Observe several parent–young child pairs in a supermarket or department store, where parents are likely to place limits on children’s behavior. How does the quality of parent communication seem to influence the child’s response? How does the child’s response affect the parent’s subsequent interaction?

Third parties can serve to enhance or impede development. For example, when a marital relationship is warm and considerate, parents are more likely to engage in coparenting, or coordination of parenting roles, that is mutually supportive and collaborative. Such parents are warmer, praise and stimulate their children more, and nag and scold them less (Morrill et al., 2010). In contrast, parents whose marriage is tense and hostile often coparent ineptly. They interfere with each other’s child-rearing efforts, are less responsive to children’s needs, and are more likely to criticize, express anger, and punish (Palkovitz, Fagan, & Hull, 2013; Stroud et al., 2015).

Children who are chronically exposed to angry, unresolved parental conflict have serious behavior problems resulting from disrupted emotional security (Cummings & Miller-Graff, 2015). These include both internalizing difficulties, such as feeling anxious and fearful and trying to repair their parents’ relationship, and externalizing difficulties, including anger and aggression (Goeke-Morey, Papp, & Cummings, 2013; Stroud et al., 2015).

Adapting to Change

Think back to the chronosystem in ecological systems theory (see page 27 in Chapter 1). The interplay of forces within the family is dynamic and ever-changing as each member adapts to the development of other members.

For example, as children acquire new skills, parents adjust the way they treat their more competent youngsters. Consider the way a parent relates to a young infant compared to a walking, talking toddler. During the first few months, parents spend much time feeding, bathing, and cuddling the baby. Within a year, things change dramatically. The 1-year-old points, shows, names objects, and explores the household cupboards. In response, parents devote more time to talking, playing games, and disciplining. These new ways of interacting, in turn, encourage the child’s expanding motor, cognitive, and social skills.

Parents’ development affects children as well. The rise in parent–child conflict that often occurs in early adolescence is not solely due to teenagers’ striving for independence. This is a time when most parents have reached middle age and—conscious that their children will soon leave home and establish their own lives—are reconsidering their own commitments (Steinberg & Silk, 2002). While the adolescent presses for greater autonomy, the parent presses for more togetherness. This imbalance promotes friction, which parent and teenager gradually resolve by accommodating to changes in each other.

Historical time period also contributes to a dynamic family system. In recent decades, a declining birth rate, a high divorce rate, expansion of women’s roles, increased acceptance of same-sex relationships, and postponement of parenthood have led to a smaller family size and a greater number of single parents, remarried parents, lesbian and gay parents, employed mothers, and dual-earner families. Clearly, families in industrialized nations have become more diverse than ever before. In later chapters, we will take up these family forms, examining how each affects family relationships and children’s development.

Nevertheless, some general patterns in family functioning do exist. In the United States and other industrialized nations, one important source of these consistencies is socioeconomic status.

2.3.2 Socioeconomic Status and Family Functioning

People in industrialized nations are stratified on the basis of what they do at work and how much they earn for doing it—factors that determine their social position and economic well-being. Researchers assess a family’s standing on this continuum through an index called socioeconomic status (SES), which combines three related, but not completely overlapping, variables: (1) years of education and (2) the prestige of one’s job and the skill it requires, both of which measure social status; and (3) income, which measures economic status. As SES rises and falls, families face changing circumstances that profoundly affect children’s development and well-being.

SES is linked to timing of parenthood and to family size. People who work in skilled and semiskilled manual occupations (for example, construction workers, truck drivers, and custodians) tend to marry and have children earlier as well as give birth to more children than people in professional and technical occupations. The two groups also differ in child-rearing values and expectations. When more than 200,000 parents in 90 nations around the world were asked about personal qualities they desire for their children, lower-SES parents more often emphasized obedience, whereas higher-SES parents placed greater weight on independence (Park & Lau, 2016). In other research, low-SES parents tended to stress external characteristics, such as politeness, neatness, and cleanliness. In contrast, higher-SES parents focused on psychological traits, such as curiosity, happiness, self-esteem, self-direction, and cognitive and social maturity (Duncan & Magnuson, 2003; Hoff, Laursen, & Tardif, 2002).

These differences are reflected in family interaction. Parents higher in SES talk to, read to, and otherwise stimulate their infants and preschoolers more and grant them greater freedom to explore. With older children and adolescents, higher-SES parents use more warmth, explanations, and verbal praise; set higher academic and other developmental goals; and allow their children to make more decisions. Commands (“You do that because I told you to”), criticism, and physical punishment occur more often in low-SES households (Bush & Peterson, 2008; Mandara et al., 2009).

Education contributes substantially to these variations. Higher-SES parents’ interest in providing verbal stimulation, nurturing inner traits, and promoting academic achievement is supported by years of schooling, during which they learned to think about abstract, subjective ideas and, thus, to invest in their children’s cognitive and social development (Mistry et al., 2008). At the same time, greater economic security enables parents to devote more time, energy, and material resources to fostering their children’s psychological characteristics (Duncan, Magnuson, & Votruba-Drzal, 2015). In diverse cultures around the world, as the Social Issues: Education box on page 68 makes clear, education of women in particular fosters patterns of thinking and behaving that greatly improve quality of life, for both parents and children.

Because of limited education and low social status, many low-SES parents feel a sense of powerlessness in their relationships beyond the home. At work, for example, they must obey rules made by others in positions of authority. When they get home, they often expect the same unquestioning obedience from their children (Belsky, Schlomer, & Ellis, 2012; Conger & Donnellan, 2007). High levels of stress sparked by economic insecurity contribute to low-SES parents’ reduced provision of stimulating interaction and activities as well as greater use of coercive discipline.

Social Issues: EducationWorldwide Education of Girls: Transforming Current and Future Generations

In 2012, Malala Yousafzai, a Pakistani teenager, rose to international prominence after surviving an assassination attempt by a Taliban gunman for her persuasive activism favoring girls’ right to education. Three years earlier, at age 11, Malala had begun writing a blog for the BBC, using a pseudonym to protect her safety. The blog reported her experiences under Taliban rule, which had at times banned girls in her province from attending school. After the New York Times released a documentary about Malala’s life and courage, she began giving interviews that were broadcast around the world. In retaliation, the Taliban gunned her down on a school bus.

Malala’s recovery from life-threatening gunshot wounds sparked worldwide support for her cause. Among the outcomes were a 2012 United Nations petition called “I am Malala,” advocating school enrollment for all the world’s children, and a UNESCO fund directed at expanding girls’ access to high-quality, safe learning environments, especially in countries affected by conflict and disaster. These initiatives led to Pakistan’s first compulsory education law, which guarantees free education to all children between ages 5 and 16.

From 1950 to 2010, the percentage of children in developing nations attending school increased from a small minority of boys to a majority of all children in most regions. Recently, however, progress has slowed. Today, 63 million (9 percent) of the world’s children of elementary-school age are not in school, a rate that climbs to 61 million (16 percent) at the middle-school level and 263 million (36 percent) at the high-school level (UNESCO, 2018). Although gender differences have declined, more girls than boys remain out of school, especially in the poorest countries. Two-thirds of the world’s 750 million illiterate adults are women.

In research carried out in four nations—Mexico, Nepal, Venezuela, and Zambia—investigators examined the impact of variations in maternal language and literacy skills on family health, mother–child interaction, and young children’s literacy skills (LeVine et al., 2012). Participating mothers’ average levels of schooling ranged from 5 years in Nepal to 8 years in Zambia, with some having attended for as little as 1 year and most having left by age 13.

Findings in each country, and across rural and urban areas, were the same. Educating girls had a powerful impact on the welfare of children and families. The diverse benefits largely accrued in two ways: (1) through enhanced verbal skills—reading, writing, and oral communication; and (2) through the cognitive abilities that literacy promotes. Together, these capacities enable girls, as they become adults and mothers, to navigate health and educational settings more effectively and to teach their children in ways that foster school success.

Child Health

Maternal education in developing countries is the most important contributor to steady, worldwide gains in children’s health over the past several decades (Denno & Paul, 2017). In the four-countries study, the higher mothers’ school attainment and literacy level, the better their comprehension of radio and TV health messages and the more easily they could explain their children’s illness symptoms to health professionals.

Clearly, education gives women the knowledge and communication skills to benefit from public health information. As a result, it strongly predicts preventive health behaviors, including prenatal visits, child immunizations, and healthy diet. Also, because women with more schooling have more life opportunities, they are more likely to take advantage of family planning services, delay childbearing, and have more widely spaced and fewer children (Günes, 2015). All these practices are linked to improvements in child survival and health.

Pakastani girls attend class on the first anniversary of the near-fatal shooting of Malalah Yousafzai, a teenage activist who advocates forcefully for education for girls. Within weeks of the assassination attempt, a shocked Pakistan enacted its first compulsory education legislation. After recovering, Malalah resumed her activism. In 2014, she was awarded the Nobel Peace Prize and, in 2017, was named a United Nations Messenger of Peace.



Educating girls is the most effective means of combating the most profound, global threats to children’s development: poverty, child mortality, disease, gender inequality, and economic and social instability in the world’s poorest countries (Tao, 2018). Even the limited educational doses available to women in the four-countries study were influential. But because of cultural beliefs about gender roles, reluctance to give up a daughter’s work at home, or war and social upheaval, parents may resist sending their daughters to school.

An even greater barrier is that many low-income countries continue to charge parents a fee for each child enrolled in school. Consequently, poverty-stricken parents—if they send any children—tend to send only sons. When governments abolish enrollment fees, provide information about the benefits of education for girls, and create employment possibilities for women, the overwhelming majority of parents—including the very poor—choose to send their daughters to school and are willing to make sacrifices to do so.

As early as the second year of life, higher SES is associated with enhanced cognitive and language development and with reduced incidence of behavior problems. And throughout childhood and adolescence, children from higher-SES families, on average, do better in school (Bradley & Corwyn, 2003; Hoff, 2013; Melby et al., 2008; Noble et al., 2015a). As a result, they usually attain higher levels of education, which greatly enhances their opportunities for a prosperous adult life.

2.3.3 Affluence

Despite their advanced education and great material wealth, affluent parents—those in prestigious and high-paying occupations—too often fail to engage in family interaction and parenting that promote favorable development. In several studies, researchers tracked the adjustment of youths growing up in wealthy suburbs. By seventh grade, many showed serious problems that worsened in high school (Luthar & Barkin, 2012; Racz, McMahon, & Luthar, 2011). Their school grades were poor, and they were more likely than youths in general to engage in alcohol and drug use, to commit delinquent acts, and to report high levels of anxiety and depression.

Why are so many affluent youths troubled? Compared to their better-adjusted counterparts, poorly adjusted affluent young people report less emotional closeness, less supervision, and fewer serious consequences for misbehaviors from their parents, who lead professionally and socially demanding lives. As a group, wealthy parents are nearly as physically and emotionally unavailable to their youngsters as parents coping with serious financial strain. At the same time, these parents often make excessive demands for achievement and are critical when their children perform less than perfectly (Luthar, Barkin, & Crossman, 2013). Adolescents whose parents value their accomplishments more than their character are more likely to have academic and emotional problems.

For both affluent and low-SES youths, a simple routine—eating dinner with parents—is associated with a reduction in adjustment difficulties, even after many other aspects of parenting are controlled (see Figure 2.7) (Luthar & Latendresse, 2005). Interventions that make wealthy parents aware of the high costs of a competitive lifestyle, weak involvement in children’s lives, and unrealistically high expectations are badly needed.

Figure 2.7 Relationship of regularly eating dinner with parents to affluent youths’ adjustment problems. Among several hundred affluent sixth graders, those who rarely ate dinner with their parents, compared with those who often did so, were far more likely to display anxiety and depression, delinquency and substance use, and poor school grades, even after many other aspects of parenting were controlled. In this study, frequent family mealtimes also protected low-SES youths from delinquency and substance use and from classroom learning problems. (Based on Luthar & Latendresse, 2005a.)

2.3.4 Poverty

When families slip into poverty, development is seriously threatened. In a TV documentary on childhood poverty, a PBS filmmaker explored the daily lives of several American children, along with the struggles of their families (Frontline, 2012). Asked what being poor is like, 10-year-old Kaylie replied, “We don’t get three meals a day…. Sometimes we have cereal but no milk and have to eat it dry.” Kaylie said she felt hungry much of the time, adding, “I’m afraid if we can’t pay our bills, me and my brother will starve.”

Kaylie lives with her 12-year-old brother Tyler and their mother, who suffers from depression and panic attacks and cannot work. The children sometimes gather discarded tin cans from around their rural neighborhood and sell them for a small amount. When money to pay rent ran out, the family moved from its small house to an extended-stay motel. Before the move, Kaylie and Tyler tearfully gave up their pet dog to a shelter.

With family belongings piled haphazardly around her in the cramped motel room, Kaylie complained, “I have no friends, no places to play. I pass the time by.” Kaylie and Tyler had few books and indoor games; no outdoor play equipment such as bicycles, bats and balls, and roller skates; and no scheduled leisure pursuits. Asked to imagine her future, Kaylie wasn’t hopeful. “I see my future poor, on the streets, in a box, asking for money from everyone, stealing stuff…. I’d like to explore the world, but I’m never going to be able to do that.”

Today, 12.7 percent of the U.S. population—nearly 41 million Americans—live in poverty. Among those hit hardest are parents under age 25 with young children, one-fourth of whom are poor. Poverty is also magnified among ethnic minorities and women. For example, 18 percent of U.S. children younger than age 18—about 12 million—live in families with incomes below the federal poverty level, the income judged necessary for a minimum living standard (about $25,000 for a family of four). Poverty rates climb to 27 percent for Hispanic children, 31 percent for African-American children, and 34 percent for Native-American children. For single mothers with preschool children, the poverty rate is close to 50 percent (Semega, Fontenot, & Kollar, 2017; U.S. Census Bureau, 2017a).

Figure 2.8 Child poverty in 20 of the world’s economically advanced nations. Among the countries listed, the United States has the highest percentage of children and youths under age 18 living in families with incomes below 60 percent of the national median income. (Based on OECD, 2018b.)

As we will see later, government programs with insufficient resources to meet family needs are responsible for these disheartening statistics. The U.S. poverty rate is higher among children than any other age group. And of all Western nations, the United States has the highest percentage of extremely poor children. Eight percent of U.S. children live in deep poverty (at less than half the poverty threshold, the income level judged necessary for a minimum living standard). In contrast, in most economically advanced nations, child poverty rates have remained well below the U.S. poverty rate for several decades (see Figure 2.8), and extreme poverty is rare (UNICEF, 2017c). The earlier poverty begins, the deeper it is, and the longer it lasts, the more devastating are its effects. Children of poverty are more likely than other children to suffer from lifelong poor physical health, persistent deficits in cognitive development and academic achievement, high school dropout, mental illness, and impulsivity, aggression, and antisocial behavior (Duncan, Magnuson, & Votruba-Drzal, 2015; Yoshikawa, Aber, & Beardslee, 2012).

The constant stressors that accompany poverty gradually weaken the family system. Poor families have many daily hassles: loss of welfare and unemployment payments, basic services—phone, TV, electricity, hot water—being shut off because of inability to pay bills, and limited or uncertain access to food, to name just a few. When daily crises arise, family members become depressed, irritable, and distracted; hostile interactions increase; and children’s development suffers (Conger & Donnellan, 2007; Kohen et al., 2008).

Negative outcomes are especially severe in single-parent families and in families who must live in run-down, overcrowded housing and dangerous neighborhoods—conditions that make everyday existence even more difficult while reducing social supports that help people cope with economic hardship (Leventhal, Dupéré, & Shuey, 2015). On average, poverty rates are higher, neighborhood disorganization greater, and community services scarcer in rural communities—like the one where Kaylie, Tyler, and their mother live—than in urban areas (Hicken et al., 2014; Vernon-Feagans & Cox, 2013). These circumstances heighten risks for disrupted family functioning and physical and psychological adjustment difficulties.

Homelessness poses enormous challenges for maintaining positive family relationships and physical and mental health. This mother and her three young children prepare to move out of the motel room they share with her boyfriend and her father.

© John Raoux/AP Images

A related problem has reduced the life chances of substantial numbers of children: More than 3 percent—nearly 2.5 million—experienced homelessness in the most recently reported year (Bassuk et al., 2014). Most homeless families consist of women with children under age 5. Besides health problems (which affect the majority of homeless people), many homeless children suffer from developmental delays and chronic emotional stress due to harsh, insecure daily lives (Kilmer et al., 2012). Homeless children achieve less less well academically than other poverty-stricken children because of poor school attendance, frequent moves from school to school, and physical and emotional health problems (Cutuli et al., 2010; National Coalition for the Homeless, 2012).

Although gaps in overall health and achievement between poverty-stricken children and their economically better-off peers are substantial, a considerable number of children from financially stressed families are resilient, faring well. A host of interventions have emerged to help children and youths surmount the risks of poverty. Some address family functioning and parenting. In a study of one such program, poverty-stricken families with preschool through adolescent children were randomly assigned to a family-strengthening intervention or to a no-intervention control group. The intervention involved 14 hours of intensive parent training devoted to learning about and practicing effective strategies for coping with stress, solving everyday problems, and engaging in positive family communication and parenting. Compared with controls, participating parents reported an improved capacity to manage stressful situations, lessening of economic strain, warmer parent–child interaction, and fewer depressive symptoms—benefits that translated into a reduction in child internalizing and externalizing difficulties (Wadsworth et al., 2013). These positive outcomes were still evident 18 months after the intervention ended.

Other interventions directly target children’s academic, emotional, and social skills in child-care centers, preschools, and elementary and secondary schools. And more programs recognize that because poverty-stricken children often experience multiple adversities, they benefit most from multifaceted efforts that focus on family, parenting, and children’s needs at once (Kagan, 2013a). We will discuss many such interventions later in this text.

2.3.5 Beyond the Family: Neighborhoods and Schools

As the concepts of mesosystem and exosystem in ecological systems theory make clear, connections between family and community are vital for psychological well-being. From our discussion of poverty, perhaps you can see why: In poverty-stricken areas, community life is often disrupted. Families move often, parks and playgrounds are in disarray, and community centers providing organized leisure-time activities do not exist. In poor urban neighborhoods, family violence, child abuse and neglect, child and youth internalizing and externalizing difficulties, and adult criminal behavior are widespread (Chen, Howard, & Brooks-Gunn, 2011; Dunn, Schaefer-McDaniel, & Ramsay, 2010; Ingoldsby et al., 2012; Lang et al., 2008). And in poor rural communities, family isolation and scarcity of supportive services are especially high (Vernon-Feagans & Cox, 2013). In contrast, strong family ties to the surrounding social context—as indicated by frequent contact with relatives and friends and regular church, synagogue, temple, or mosque attendance—reduce stress and enhance adjustment.


Neighborhoods offer resources and social ties that play an important part in children’s development. In an experimental study of neighborhood mobility, low-SES families were randomly assigned vouchers to move out of public housing into neighborhoods varying widely in affluence. Compared with their peers who remained in poverty-stricken areas, children and youths who moved into low-poverty neighborhoods and remained there for at least several years showed better physical and mental health and school achievement. Children exposed to advantaged neighborhoods consistently, from early childhood into adolescence, benefit the most academically (Anderson & Leventhal, 2014; Leventhal & Brooks-Gunn, 2003; Leventhal & Dupéré, 2011). The ability of low-income families to integrate into the social life of their new neighborhoods is also key to favorable outcomes.

Neighborhood resources have a greater impact on economically disadvantaged than on well-to-do young people. Higher-SES families can afford to transport their children to lessons and entertainment and, if necessary, to better-quality schools in distant parts of the community. In low-income neighborhoods, in-school and after-school programs that substitute for lack of other resources by providing art, music, sports, and other enrichment activities are associated with improved academic performance and a reduction in emotional and behavior problems in elementary and middle school (Durlak, Weissberg, & Pachan, 2010; Kataoka & Vandell, 2013; Vandell, Reisner, & Pierce, 2007). Neighborhood organizations, such as religious youth groups and special interest clubs, contribute to favorable development in adolescence, including increased self-confidence, school achievement, and educational aspirations (Barnes et al., 2007).

Look and Listen

Ask several parents to list their school-age children’s regular lessons and other enrichment activities. Then inquire about home and neighborhood factors that either encourage or impede their children’s participation.

Yet in dangerous, disorganized neighborhoods, high-quality activities for children and adolescents are scarce. Even when they are available, crime and social disorder limit young people’s access, and parents overwhelmed by financial and other stressors are unlikely to encourage their children to participate. In an investigation of a large sample of elementary school students diverse in SES and neighborhood residence, those living in the least stimulating homes and the most chaotic neighborhoods were least likely to enroll in after-school and community-center enrichment activities (Dearing et al., 2009). Thus, the neediest children and youths were especially likely to miss out on these development-enhancing experiences.

Just how do family–neighborhood ties reduce parenting stress and promote children’s development? One answer lies in their provision of social support, which leads to the following benefits:

Parental self-worth. A neighbor or relative who listens and tries to relieve a parent’s concern enhances her self-esteem. The parent, in turn, is likely to interact in a more sensitive and involved manner with her children.

Parental access to valuable information and services. A friend who suggests where a parent might find a job, housing, and affordable child care and youth activities helps make the multiple roles of spouse, parent, and provider easier to fulfill.

Child-rearing controls and role models. Friends, relatives, and other community members may encourage and demonstrate effective parenting practices and discourage ineffective practices.

Direct assistance with child rearing. As children and adolescents participate in their parents’ social networks and in neighborhood settings, other adults can influence children through warmth, stimulation, and exposure to a wider array of competent models. In this way, family–neighborhood ties can reduce the impact of ineffective parenting (Silk et al., 2004). Nearby adults can also intervene when they see young people skipping school or behaving antisocially.

The Better Beginnings, Better Futures Project of Ontario, Canada, is a government-sponsored initiative aimed at preventing the dire consequences of neighborhood poverty by strengthening community capacity to create development-enhancing environments for children and families. Using neighborhood elementary schools as its base, Better Beginnings programs provided children ages 4 to 8 years with in-class, before- and after-school, and summer enrichment activities. Program staff also visited each child’s parents regularly, informed them about community resources, and encouraged their involvement in the child’s school and neighborhood life. And a communitywide component focused on improving neighborhood life by offering leadership training and adult education programs and organizing special events and celebrations (Peters, 2005; Peters, Petrunka, & Arnold, 2003).

High-school volunteers take part in a program to clean up and revitalize Detroit’s distressed Brightmoor neighborhood. Participation in such neighborhood organizations contributes to favorable development of economically disadvantaged adolescents.

© Jim West/Alamy Stock Photo

Longitudinal follow-ups of Better Beginnings as participants reached grades 3, 6, 9, and 12 revealed wide-ranging benefits compared with children and families living in impoverished neighborhoods without this set of programs (Peters et al., 2010; Worton et al., 2014). Among these were gains in children’s academic performance and social adjustment, a reduction in adolescent delinquency and drug use, and parent-reported improved family functioning, child-rearing practices, and sense of community connection.


Unlike the informal worlds of family and neighborhood, the school is a formal institution designed to transmit knowledge and skills needed to become productive members of society. Children and youths in the developed world spend much time in school—a total of about 14,000 hours, on average, by high school graduation. And today, because many children younger than age 5 attend “school-like” child-care centers or preschools, the impact of schooling begins earlier and is even more powerful than these figures suggest.

Schools are complex social systems that affect many aspects of development. Schools vary in their physical environments—space, equipment, and materials available for work and play. They also differ in their educational philosophies—whether teachers regard students as passive learners to be molded by adult instruction; as active, curious beings who determine their own learning; or as collaborative partners assisted by adult experts, who guide their mastery of new skills. The social life of schools varies as well—in the degree to which students cooperate and compete; in the extent to which students of different abilities and SES and ethnic backgrounds learn together; and in whether they are safe, humane settings or riddled with peer harassment and violence. We will discuss these aspects of schooling in later chapters.

As with SES and family functioning, schooling and academic achievement contribute substantially to life chances and well-being. Furthermore, these contextual influences are interrelated: Children from homes in low-income and poverty-stricken neighborhoods are more likely to attend underfunded schools and experience poorer quality education. For these reasons, educational interventions aimed at upgrading the educational experiences and school performance of economically disadvantaged children are best begun in the early years (Crosnoe & Benner, 2015). But intervening at later periods to target specific educational problems is also helpful—for example, by promoting academic self-confidence and motivation in middle childhood and providing high-quality vocational education to non-college-bound youths.

Students whose parents are involved in their education—through participating in school organizations, volunteering at school, attending parent–teacher conferences, and reinforcing school-based learning at home—show better academic achievement. And when followed up in early adulthood, their educational attainment is higher (Benner, Boyle, & Sadler, 2016). Higher-SES parents, whose backgrounds and values are similar to those of teachers, are more likely to sustain regular educational involvement. In contrast, low-SES parents often feel uncomfortable about coming to school and approaching teachers on behalf of their children’s learning, and daily stressors reduce the time and energy they have to do so (Calarco, 2014; Grant & Ray, 2010). Teachers and administrators must take extra steps with low-SES and ethnic minority families to build supportive family–school ties.

2.3.6 The Cultural Context

Our discussion in Chapter 1 emphasized that child development can be fully understood only when viewed in its larger cultural context. In the following sections, we expand on this theme by taking up the role of the macrosystem in development. First, we discuss ways that cultural values and practices affect contexts for development. Then we consider how healthy development depends on laws and government programs that shield children from harm and foster their well-being.

Cultural Values and Practices

Cultures shape family interaction and community settings beyond the home—in short, all aspects of daily life. Many of us remain blind to aspects of our own cultural heritage until we see them in relation to the practices of others.

Consider the question, Who should be responsible for rearing young children? How would you answer it? Here are some common responses from my students: “If parents decide to have a baby, then they should be ready to care for it.” “Most people are not happy about others intruding into family life.” These statements reflect a widely held opinion in the United States—that the care and rearing of children, and paying for that care, are the duty of parents, and only parents. This view has a long history—one in which independence, self-reliance, and the privacy of family life emerged as basic American values (Dodge & Haskins, 2015). It is one reason, among others, that the public has been slow to endorse government-supported benefits for all families, such as high-quality child care and paid employment leave for meeting family needs. It has also contributed to the large number of U.S. children who remain poor, even though their parents are employed (Gruendel & Aber, 2007; UNICEF, 2017c).

Although the culture as a whole may value independence and privacy, not all citizens share the same values. Some belong to subcultures—groups of people with beliefs and customs that differ from those of the larger culture. Many ethnic minority groups in the United States have cooperative family structures, illustrated by the active, involved extended-family bonds common in African-American, Asian, Hispanic, and Native-American subcultures. Within these extended families, grandparents play meaningful roles in guiding younger generations; adults who face employment, marital, or parenting difficulties receive assistance and emotional support; and children are better adjusted, academically and socially (Jones & Lindahl, 2011; Washington, Gleeson, & Rulison, 2013). In Hispanic extended families, grandparents are especially likely to share in child rearing—a collaborative parenting arrangement that is consistent with the Hispanic cultural ideal of familism, which places a particularly high priority on close, harmonious family relationships. As the Cultural Influences box on page 75 indicates, familism is associated with multiple positive developmental outcomes.

Our discussion so far reflects two broad sets of values on which cultures and subcultures are commonly compared: collectivism versus individualism (Triandis & Gelfand, 2012). In cultures that emphasize collectivism, people stress group goals over individual goals and value interdependent qualities, such as interpersonal harmony, obligations and responsibility to others, and collaborative endeavors. In cultures that emphasize individualism, people are largely concerned with their own personal needs and value independence—personal exploration, discovery, achievement, and choice in relationships.

Cultural InfluencesFamilism Promotes Competence in Hispanic Children and Youths

Here are some responses from Dominican, Mexican, and Puerto Rican parents who were asked to describe their most basic values:

You have to help each other out, be there for each other, especially when you’re growing up or when you have families. I mean that togetherness is very important.

Your parents are number one but your grandparents are even greater than number one [in reference to extended family members who play a significant role in a child’s life].

When I was growing up, you had to be crazy to talk back to your parents. No one got away with that kind of falta de respeto [lack of respect] (Calzada, 2010).

Each of these statements expresses the Hispanic core cultural value of familism, which elevates the needs of family above any concerns of the individual. Familism requires family members to establish loyal, cohesive relationships with one another; to be respectful, especially toward elders; and to provide one another with emotional and material support. Familism also holds that the quality of relationships forged with family members is central to each person’s self-esteem and identity. Consequently, frequent contact is the norm in Hispanic extended families (Calzada, Tamis-LeMonda, & Yoshikawa, 2013). As they fulfill the obligations of familism in their everyday lives, many Hispanic adults live in close proximity to or share living arrangements with extended kin.

Parents begin to instill familism in young children by insisting that they interact respectfully with adults through polite greetings, not interrupting, and not challenging what they say (Stein et al., 2014). Mothers strongly committed to familism report greater warmth and closeness with their preschoolers. In one study, the combination of high maternal warmth and valuing of familism predicted better classroom emotional adjustment and peer relations among Mexican-American preschoolers (Gamble & Modry-Mandell, 2008). By emphasizing cohesiveness, support, and respect, familism seems to foster both positive parent–child interaction and preschoolers’ favorable social behavior.

From these early parental teachings, school-age children and adolescents internalize the value of familism, which further supports social competence (Bridges et al., 2012). In an investigation of Mexican-American 9- to 13-year-olds, those whose mothers exposed them to social learning opportunities consistent with familism—such as helping with sibling caregiving or meeting elder family members’ needs—expressed stronger familism beliefs (Calderón-Tena, Knight, & Carlo, 2011). Together, these parenting practices and children’s consequent familism beliefs predicted children’s willingness to help and support peers and others outside the family.

As their adolescent children become more autonomous, Hispanic parents engage in many parenting strategies consistent with familism, including closely monitoring teenagers’ activities, insisting that they follow reasonable rules, and expressing warmth and support (Stein et al., 2015; Updegraff et al., 2012). Although striving for autonomy typically leads to a decline in familism beliefs over the teenage years, young people nevertheless continue to demonstrate many behaviors consistent with familism, including spending considerable time with family members and willingly fulfilling family obligations (Updegraff et al., 2005).

Adolescents’ commitment to familism is linked to diverse aspects of maturity and adjustment. These include greater likelihood of viewing parents as legitimate sources of guidance; higher academic motivation and school grades; greater sense of school belonging; fewer deviant peer associations and risky behaviors; less anxiety and fearfulness; and less anger and aggression (Ayón, Marsiglia, & Bermudez-Parsai, 2010; Sánchez, Colón, & Esparza, 2005; Sánchez et al., 2010; Stein & Polo, 2014; Stein et al., 2015). If family responsibilities become excessive, teenagers can react with stress, depression, and worsening school performance. But overall, familism beliefs seem to make young people more aware of others’ needs and the importance of behaving respectfully and responsibly in contexts beyond the home.

Neighborhood familism—the extent to which Hispanic mothers and fathers in the same neighborhood endorse familism—is a stronger predictor of positive adolescent adjustment than family income and neighborhood economic status (Gonzales et al., 2010). Living in a community in which many adults value familism may provide youths with collective supervision and other supports for favorable development.

Although it is the most common basis for comparing cultures, the collectivism–individualism distinction is controversial because both sets of values exist in most cultures. As societies change, due to immigration and contact with other cultural, political, and economic systems, the values of their people diversify, yielding varying mixtures of collectivism and individualism (Taras et al., 2014). Integration of the two sets of values is positive for children’s development because collectivism fosters access to social support, whereas individualism promotes striving for personal goals (Chen, 2015). Both are vital for psychological well-being.

Nevertheless, consistent cross-national differences in collectivism–individualism remain: The United States is more individualistic than most Western countries, which place greater weight on collectivism. These value priorities affect a nation’s approach to protecting the well-being of children and families.

Public Policies and Child Development

When widespread social problems arise, such as poverty, hunger, and disease, nations attempt to solve them through devising public policies—laws and government programs designed to improve current conditions. In the United States, public policies safeguarding children and youths have lagged behind policies in other developed nations. As Table 2.3 reveals, the United States does not rank well on important key measures of children’s health and well-being.

The problems of children and youths extend beyond the indicators in the table. The U.S. Affordable Care Act, signed into law in 2010, extended government-supported health insurance to all children in low-income families. But expanded coverage for low-income adults, including parents, is not mandatory for the states, leaving millions of low-income parents without an affordable coverage option. Largely because uninsured parents lack knowledge of how to enroll their children, 11 percent of children eligible for the federally supported Children’s Health Insurance Program (CHIP)—more than 5 million—do not receive coverage (Kaiser Family Foundation, 2015, 2017). Furthermore, the United States has been slow to move toward national standards and funding for child care. Affordable care is in short supply, and much of it is mediocre to poor in quality (Burchinal, 2018; Burchinal et al., 2015). In families affected by divorce, weak enforcement of child support payments heightens poverty in mother-headed households. And 8 percent of 16- to 24-year-olds who dropped out of high school have not returned to earn a diploma (U.S. Department of Education, 2017b).

Why have attempts to help children and youths been difficult to realize in the United States? Cultural values of self-reliance and privacy have made government hesitant to become involved in family matters. Furthermore, good social programs are expensive, and they must compete for a fair share of a country’s economic resources. Children can easily remain unrecognized in this process because they cannot vote or speak out to protect their own interests (Ripple & Zigler, 2003). They must rely on the goodwill of others to become an important government priority.

Table 2.3 How Does the United States Compare to Other Nations on Indicators of Children’s Health and Well-Being?


U.S. Rankª

Some Countries the United States Trails

Childhood poverty (among 20 economically advanced nations with similar standards of living)


Canada, Iceland, Germany, United Kingdom, Norway, Sweden, Spain

Infant deaths in the first year of life (among 39 industrialized nations considered)


Canada, Greece, Hungary, Ireland, Spain

Teenage birth rate (among 20 industrialized nations considered)


Australia, Canada, Czech Republic, Denmark, Hungary, Iceland, Poland, Slovakia

Public expenditure on elementary education as a percentage of gross domestic productb (among 35 industrialized nations considered)


Belgium, France, Iceland, New Zealand, Portugal, Spain, Sweden

Public expenditure on early childhood education as a percentage of gross domestic productb (among 28 industrialized nations considered)


Austria, Chile, Germany, Italy, France, Sweden, Slovenia

Public expenditure on health as a percentage of total health expenditure, public plus private (among 35 industrialized nations considered)


Austria, Australia, Canada, France, Hungary, Iceland, Switzerland, New Zealand

a 1 = highest, or best, rank.

b Gross domestic product is the value of all goods and services produced by a nation during a specified time period. It provides an overall measure of a nation’s wealth.

Sources: OECD, 2017a, 2017b; Sedgh et al., 2015; UNICEF, 2017c; U.S. Census Bureau, 2017a; World Bank, 2018a.

Looking Toward the Future

Public policies aimed at fostering children’s development can be justified on two grounds. The first is that children are the future—the parents, workers, and citizens of tomorrow. Investing in children yields valuable returns to a nation’s quality of life. Second, child-oriented policies can be defended on humanitarian grounds—children’s basic rights as human beings.

In 1989, the United Nations General Assembly, with the assistance of experts from many child-related fields, drew up the Convention on the Rights of the Child, a legal agreement among nations that commits each cooperating country to work toward guaranteeing environments that foster children’s development, protect them from harm, and enhance their community participation and self-determination. Examples of rights include the highest attainable standard of health; an adequate standard of living; free and compulsory education; a happy, understanding, and loving family life; protection from all forms of abuse and neglect; and freedom of thought, conscience, religion, and expression, subject to appropriate parental guidance and national law.

Public policies fostering development are vital both on humanitarian grounds and as an investment in the future. Upward Bound—a federally funded educational enrichment program—helps prepare high school students from low-income families for successful admission to college. Here, an Upward Bound 16-year-old (right) attending a university-sponsored program on marine conservation assists a researcher during a shark-tagging expedition.


The United States played a key role in drawing up the Convention, yet it is the only country in the world whose legislature has not ratified it. American individualism has stood in the way (Ruck et al., 2014; Scherrer, 2012). Opponents maintain that the Convention’s provisions would shift the burden of child rearing from family to state.

Although the worrisome state of many children and families persists, efforts are being made to improve their condition. Throughout this book, we will discuss many successful programs that could be expanded. Also, growing awareness of the gap between what we know and what we do to better children’s lives has led experts in child development to join with concerned citizens as advocates for more effective policies. As a result, influential interest groups devoted to the well-being of children have emerged.

In the United States, one of the most vigorous is the Children’s Defense Fund (CDF),, a nonprofit organization that engages in public education and partners with other organizations, communities, and elected officials to improve policies for children and adolescents. Another energetic advocacy organization is the National Center for Children in Poverty,, dedicated to advancing the economic security, health, and welfare of U.S. children in low-income families.

Besides strong advocacy, public policies that enhance development depend on research that documents needs and evaluates programs to spark improvements. Today, more researchers are collaborating with community and government agencies to enhance the relevance of their investigations to public policies aimed at ensuring children’s rights and improving their lives (SRCD Equity and Justice Committee, 2018). Investigators are also doing a better job of disseminating their findings in easily understandable, compelling ways, through reports to government officials, websites aimed at increasing public understanding, and collaborations with the media to ensure accurate and effective reporting. In these ways, researchers are helping to create the sense of immediacy about the condition of children and families that is necessary to spur a society into action.

Ask Yourself

Connect ■ How does poverty affect functioning of the family system, placing all domains of development at risk?

Apply ■ Check your local newspaper or one or two national news websites to see how often articles appear on the condition of children and families. Why is it important for researchers to communicate with the public about children’s needs?

Reflect ■ Do you agree with the widespread American sentiment that government should not become involved in family life? Explain.


2.4 Explain the various ways heredity and environment may combine to influence complex traits.

Throughout this chapter, we have discussed a wide variety of genetic and environmental influences, each of which has the power to alter the course of development. Yet children who are born into the same family, and who therefore share both genes and environments, are often quite different in characteristics. We also know that some individuals are affected more than others by their homes, neighborhoods, and communities. In some cases, a child who is given many advantages nevertheless does poorly, while another, though exposed to unfavorable rearing conditions, does well. How do scientists explain the impact of heredity and environment when they seem to operate in such varied ways?

Behavioral genetics is a field devoted to uncovering the contributions of nature and nurture to this diversity in human traits and abilities. Although scientists are making progress in identifying the multiple variations in DNA sequences associated with such complex attributes as intelligence and personality, so far these genetic markers explain only a small amount of variation in human behavior, and a minority of cases of most psychological disorders (Plomin et al., 2016; Zhao & Castellanos, 2016). For the most part, scientists are still limited to investigating the impact of genes on these characteristics indirectly.

Some believe that it is useful and possible to answer the question of how much each factor contributes to differences among people. A growing consensus, however, regards that question as unanswerable. These investigators believe that heredity and environment are inseparable (Lickliter & Honeycutt, 2015; Moore, 2013). The important question, they maintain, is how nature and nurture work together. Let’s consider each position in turn.

2.4.1 The Question, “How Much?”

To infer the role of heredity in complex human characteristics, researchers use special methods, the most common being the heritability estimate. Let’s look closely at the information this procedure yields, along with its limitations.


Heritability estimates measure the extent to which individual differences in complex traits in a specific population are due to genetic factors. We will take a brief look at heritability findings on intelligence and personality here, returning to them in greater detail in later chapters. Heritability estimates are obtained from kinship studies, which compare the characteristics of family members. The most common type of kinship study compares identical twins, who share all their genes, with fraternal twins, who, on average, share only half. If people who are genetically more alike are also more similar in intelligence and personality, then the researcher assumes that heredity plays an important role.

Kinship studies of intelligence provide some of the most controversial findings in the field of developmental science. Some experts claim a strong genetic influence, whereas others believe that heredity is barely involved. Currently, most kinship findings support a moderate role for heredity. When many twin studies are examined, correlations between the scores of identical twins are consistently higher than those of fraternal twins. In a summary of more than 10,000 twin pairs of diverse ages, the correlation for intelligence was.85 for identical twins and.60 for fraternal twins (Plomin & Spinath, 2004; Plomin et al., 2016).

Researchers use a complex statistical procedure to compare these correlations, arriving at a heritability estimate ranging from 0 to 1.00. The typical overall heritability estimate for intelligence is about.50 for child and adolescent twin samples in Western industrialized nations, suggesting that differences in genetic makeup explain half the variation in intelligence. However, heritability increases with age, from approximately.20 in infancy, to.40 in childhood, to.55 in adolescence, to.65 in early adulthood (Plomin & Deary, 2015). As we will see later, one explanation is that, compared to children, adolescents and adults exert greater personal control over their intellectual experiences—for example, how much time they spend reading or solving challenging problems. Adopted children’s intelligence test scores are more strongly related to their biological parents’ scores than to those of their adoptive parents, offering further support for the role of heredity (Petrill & Deater-Deckard, 2004).

Heritability research also reveals that genetic factors are important in personality. For frequently studied traits, such as sociability, anxiety, agreeableness, and activity level, heritability estimates obtained on child, adolescent, and young adult twins are moderate, in the.40s and.50s (van Beijsterveldt et al., 2016; Vukasović & Bratko, 2015). Unlike intelligence, however, heritability of personality does not increase with age (Turkheimer, Pettersson, & Horn, 2014).

Celena Kopinski (left) and Sarah Heath (right) were born in China and adopted during their first year into different American families. Both were unaware they were related until, during Sarah’s first year of college, a classmate called her by the wrong name and sent a photo of her to Celena. Two years later, when the adoptees met, DNA testing confirmed that they are identical twins. About getting to know each other, Celena commented, “It’s kind of like looking in the mirror, except there is no mirror!” They discovered striking similarities, including the same taste in fashion. Clearly, heredity contributes to personality, but generalizing from twin evidence to the population is controversial.


Twin studies of schizophrenia, bipolar disorder, and autism generally yield high heritabilities, above.70. Heritabilities for antisocial behavior and major depression are considerably lower, in the.30s and.40s (Ronald & Hoekstra, 2014; Sullivan, Daly, & O’Donovan, 2012). Again, adoption studies are consistent with these results. Biological relatives of adoptees with schizophrenia, bipolar disorder, or autism are more likely than adoptive relatives to share the same disorder (Plomin, DeFries, & Knopik, 2013).

Limitations of Heritability

The accuracy of heritability estimates depends on the extent to which the twin pairs studied reflect genetic and environmental variation in the population. Within a population in which all people have very similar home, school, and community experiences, individual differences in intelligence and personality are assumed to be largely genetic, and heritability estimates should be close to 1.00. Conversely, the more environments vary, the more likely they are to account for individual differences, yielding lower heritability estimates. In twin studies, most twin pairs are reared together under highly similar conditions. Even when separated twins are available for study, social service agencies have often placed them in advantaged homes that are alike in many ways (Charney, 2017; Richardson & Norgate, 2006). Because the environments of most twin pairs are less diverse than those of the general population, heritability estimates are likely to exaggerate the role of heredity.

Heritability estimates can easily be misapplied. For example, high heritabilities have been used to suggest that ethnic differences in intelligence test scores, such as the poorer performance of African-American children compared to European-American children, have a genetic basis (Jensen, 1969, 2001; Rushton, 2012). Yet heritabilities computed on mostly White twin samples do not explain test score differences between ethnic groups. We have already seen that large SES differences are involved. In Chapter 12, we will discuss research indicating that when African-American children are adopted into economically advantaged homes at an early age, their scores are well above average and substantially higher than those of children growing up in impoverished families.

Consistent with these findings, the heritability of children’s intelligence increases as parental education and income increase—that is, as children grow up in conditions that allow them to make the most of their genetic endowment. In impoverished environments, children are prevented from realizing their potential. Consequently, enhancing these children’s experiences through interventions—such as parent education and high-quality preschool or child care—has a greater impact on development (Bronfenbrenner & Morris, 2006; Phillips & Lowenstein, 2011).

2.4.2 The Question, “How?”

Today, most researchers view development as the result of a dynamic interplay between heredity and environment. How do nature and nurture work together? Several concepts shed light on this question.

Gene–Environment Interaction

The first of these ideas is gene–environment interaction, which means that because of their genetic makeup, individuals differ in their responsiveness to qualities of the environment (Rutter, 2011). Gene–environment interaction can apply to any characteristic; it is illustrated for intelligence in Figure 2.9. Notice that when environments vary from extremely unstimulating to highly enriched, Ben’s intelligence increases steadily, Linda’s rises sharply and then falls off, and Ron’s begins to increase only after the environment becomes modestly stimulating.

Gene–environment interaction highlights two important points. First, it shows that because each of us has a unique genetic makeup, we respond differently to the same environment. Notice in Figure 2.9 how a poor environment results in similarly low scores for all three individuals. But when the environment provides a moderate level of simulations, Linda is by far the best-performing child. In a highly enriched environment, Ben does best, followed by Ron, both of whom now outperform Linda. Second, sometimes different gene–environment combinations can make two people look the same! For example, if Linda is reared in a minimally stimulating environment, her score will be about 100—average for people in general. Ben and Ron can also obtain this score, but to do so, they must grow up in fairly enriched circumstances (Gottlieb, Wahlsten, & Lickliter, 2006).

Figure 2.9 Gene–environment interaction, illustrated for intelligence by three children who differ in responsiveness to quality of the environment. As environments vary from extremely unstimulating to highly enriched, Ben’s intelligence test score increases steadily, Linda’s rises sharply and then falls off, and Ron’s begins to increase only after the environment becomes modestly stimulating.

Recently, researchers have made strides in identifying gene–environment interactions in personality development. In Chapter 7 we will see that young children with certain genes that increase their risk of an emotionally reactive temperament respond especially strongly to variations in parenting quality (Bakermans-Kranenburg & van IJzendoorn, 2015; Halldorsdottir & Binder, 2017). When parenting is supportive, they gain control over their emotions and adjust as well or better than other children. But when parenting is harsh and insensitive, they become increasingly irritable, difficult, and poorly adjusted, more so than children not at genetic risk. Notice how such children are genetically constituted to react to both positive and negative parenting with especially high plasticity.

Gene–Environment Correlation

A major problem in trying to separate heredity and environment is that they are often correlated (Rutter, 2011; Scarr & McCartney, 1983). According to the concept of gene–environment correlation, our genes influence the environments to which we are exposed. The way this happens changes with age.

Passive and Evocative Correlation

At younger ages, two types of gene–environment correlation are common. The first is called passive correlation because the child has no control over it. Early on, parents provide environments influenced by their own heredity. For example, parents who are good athletes emphasize outdoor activities and enroll their children in swimming and gymnastics. Besides being exposed to an “athletic environment,” the children may have inherited their parents’ athletic ability. As a result, they are likely to become good athletes for both genetic and environmental reasons.

The second type of gene–environment correlation is evocative. Children evoke responses that are influenced by their heredity, and these responses strengthen their original behavior pattern. For example, an active friendly baby is likely to receive more social stimulation than a passive, quiet infant. And a cooperative, attentive child probably receives more sensitive, patient interactions from parents than an inattentive, distractible child. In support of this idea, the more genetically alike siblings are, the more their parents treat them alike, in both warmth and negativity. Parents’ treatment of identical twins is highly similar, whereas their treatment of fraternal twins and nontwin biological siblings is only moderately so. And little resemblance exists in parents’ warm and negative interactions with unrelated stepsiblings (Reiss, 2003). Likewise, identical-twin pairs—who resemble each other more in sociability than fraternal twins do—tend to be more alike in the degree of friendliness they evoke from new playmates (DiLalla, Bersted, & John, 2015).

Active Correlation

At older ages, active gene–environment correlation becomes common. As children extend their experiences beyond the immediate family and are given the freedom to make more choices, they actively seek environments that fit with their genetic tendencies. The well-coordinated, muscular child spends more time at after-school sports, while the intellectually curious child is a familiar patron at the local library.

This tendency to actively choose environments that complement our heredity is called niche-picking (Scarr & McCartney, 1983). Infants and young children cannot do much niche-picking because adults select environments for them. In contrast, older children and adolescents are increasingly in charge of their own environments.

A mother imparts her ceramic skills to her daughter, who may have inherited her mother’s artistic ability. When heredity and environment are correlated, the influence of one cannot be separated from the influence of the other.

© Albert Shakirov/Alamy Stock Photo

Niche-picking explains why pairs of identical twins reared apart during childhood and later reunited may find, to their surprise, that they have similar hobbies, food preferences, and vocations—a trend that is especially marked when twins’ environmental opportunities are similar. Niche-picking also helps us understand why identical twins become somewhat more alike, and fraternal twins and adopted siblings less alike, in intelligence with age (Bouchard, 2004). And niche-picking sheds light on why identical twin pairs—far more often than same-sex fraternal twin pairs—report similar stressful life events influenced by personal decisions and actions, such as failing a course or getting in trouble for drug-taking (Bemmels, et al., 2008).

The influence of heredity and environment is not constant but changes over time. With age, genetic factors may become more important in influencing the environments we experience and choose for ourselves.

Environmental Influences on Gene Expression

Notice how, in the concepts just considered, heredity is granted priority. In gene–environment interaction, it affects responsiveness to particular environments. Similarly, gene–environment correlation is viewed as driven by genetics, in that children’s genetic makeup causes them to receive, evoke, or seek experiences that actualize their hereditary tendencies (Rutter, 2011).

A growing number of researchers contend that heredity does not dictate children’s experiences or development in a rigid way. For example, in a large Finnish adoption study, children with a genetic tendency for mental illness (based on having a biological mother diagnosed with schizophrenia) but who were being reared by healthy adoptive parents showed little mental illness. In contrast, schizophrenia and other psychological impairments piled up in adoptees whose biological and adoptive parents were both mentally ill (Tienari, Wahlberg, & Wynne, 2006; Tienari et al., 2003).

Furthermore, parents and other caring adults can uncouple unfavorable gene–environment correlations by providing children with positive experiences that modify the expression of heredity, yielding positive outcomes. In an investigation that tracked the development of 5-year-old identical twins, pair members tended to resemble each other in level of aggression. The more aggression children displayed, the more maternal anger and criticism they received (a gene–environment correlation). Nevertheless, some mothers treated their twins differently. When followed up at age 7, twins who had been targets of more maternal negativity engaged in even more aggressive behavior. In contrast, their better-treated counterparts showed a reduction in disruptive acts (Caspi et al., 2004). Good parenting protected them from a spiraling, antisocial course of development.

Accumulating evidence reveals that the relationship between heredity and environment is not a one-way street, from genes to environment to behavior. Rather, like other system influences considered in this and the previous chapter, it is bidirectional: Genes affect people’s behavior and experiences, but their experiences and behavior also affect gene expression. Stimulation both external to the child (home, neighborhood, school, and society) and internal to the child (activity within the cytoplasm of the cell, hormones released into the bloodstream) modifies gene activity.

This view of the relationship between heredity and environment, depicted in Figure 2.10, is called epigenesis, which means development resulting from ongoing, bidirectional exchanges between heredity and all levels of the environment (Cox, 2013; Gottlieb, 1998, 2007). Biologists are clarifying the precise mechanisms through which environment can alter gene expression without changing the DNA sequence—a field of research called epigenetics. The most highly studied mechanism is methylation—a biochemical process triggered by certain experiences, in which a set of chemical compounds (called a methyl group) lands on top of a gene and changes its impact, reducing or silencing its expression. Methylation levels can be measured, and they help explain why identical twins, though precisely the same in DNA sequencing, sometimes display strikingly different phenotypes with age.

Figure 2.10 Epigenesis. Development takes place through ongoing, bidirectional exchanges between heredity and all levels of the environment. Genes affect behavior and experiences. Experiences and behavior also affect gene expression. (Based on Gottlieb, 2007.)

A case study of a pair of identical-twin adults offers an illustration. Researchers reported that they had been highly similar in personality throughout childhood. But after high school, one twin remained close to home, studied law, married, and had children, whereas the other left home, became a journalist, and traveled to war zones around the world, where she repeatedly encountered life-threatening situations. Assessed again in their forties, compared with the “law twin,” the “war twin” engaged in more risky behaviors, including drinking and gambling (Kaminsky et al., 2007). DNA analyses revealed greater methylation of a gene known to affect impulse control in the “war twin” than in the “law twin”—a difference much larger than is typical for identical-twin pairs.

Environmental modification of gene expression can occur at any age, even prenatally. Recall our discussion of genomic imprinting on page 57. It is an epigenetic process occurring within the ovum or sperm, often involving methylation. And one way harmful prenatal environmental factors we will address in Chapter 3 may compromise development is through gene methylation (Markunas et al., 2014). As the Biology and Environment box on page 83 illustrates, severe maternal stress during pregnancy is linked to long-term impairment in children’s capacity to manage stress, with gene methylation likely contributing to unfavorable outcomes. Furthermore, animal evidence indicates that some methylated genes are passed to offspring at conception, thereby affecting development in subsequent generations (Grossniklaus et al., 2013).

We must keep in mind, however, that epigenetic processes also operate positively: Favorable rearing experiences alter gene expression in ways that enhance development! And some negative epigenetic modifications may be reversible through carefully designed interventions (Boyce & Kobor, 2015; van IJzendoorn, Bakermans-Kranenburg, & Ebstein, 2011). The concept of epigenesis reminds us that the genome is constantly in flux, both reflecting and affecting the individual’s ever-changing environment.

The relationship between heredity and environment is bidirectional. This child’s genetic makeup might predispose her to heart disease or obesity. But favorable experiences—such as participation in sports programs that promote regular, vigorous exercise—might alter gene expression in ways that overcome this genetic susceptibility.

KIKE CALVO / Alamy Stock Photo

Biology and EnvironmentThe Tutsi Genocide and Epigenetic Transmission of Maternal Stress to Children

In 1994, in a genocidal rampage against the Tutsi people of Rwanda, nearly 1 million people perished within a three-month period. The horror was so extreme that in surveys of Rwandans during the years following the genocide, an estimated 40 to 60 percent reported symptoms of post-traumatic stress disorder (PTSD) (Neugebauer et al., 2009; Schaal et al., 2011). In PTSD, flashbacks, nightmares, anxiety, irritability, angry outbursts, and difficulty concentrating lead to intense distress, physical symptoms, and loss of interest in relationships and daily life.

Parents with PTSD often have children with PTSD (Brand et al., 2011; Morris, Gabert-Quillen, & Delahanty, 2012). In both children and adults, PTSD is associated with disruptions in the body’s stress response system, reflected in abnormal blood levels of the stress hormone cortisol. In appropriate concentrations, cortisol assists our brains in managing stress effectively. In individuals with PTSD, cortisol levels are either too high or (more often) too low, contributing to persistently disturbed stress regulation.

Figure 2.11 Methylation status of the GR gene in trauma-exposed and non-trauma-exposed Tutsi mothers and their children. Mothers who had been directly exposed to the Rwandan Tutsi genocide, as well as their children, showed elevated methylation of the GR gene, which is centrally involved in functioning of the body’s stress response system. (Based on Perroud et al., 2014.)

Mounting evidence confirms that exposure to extreme adversity increases methylation of a chromosome-5 gene called GR, which plays a central role in stress-hormone regulation. Might this epigenetic process contribute to parent–to–child transmission of PTSD?

To explore this question, researchers identified 50 Tutsi women who had been pregnant during the genocide (Perroud et al., 2014). Half had been directly exposed to the trauma; the other half had been out of the country at the time. Eighteen years later, the mothers and their adolescent children were assessed for PTSD and depression by trained psychologists. Blood samples enabled genetic testing for methylation of the GR gene and assessment of cortisol levels.

Compared with non-exposed mothers, mothers who witnessed the genocidal carnage had substantially higher PTSD and depression scores, and children of the two groups of mothers differed similarly. Also, as Figure 2.11 reveals, exposed mothers and their children displayed stronger GR methylation. And consistent with methylation’s dampening effect on gene expression, trauma-exposed mothers and their children had much lower cortisol levels than their non-exposed counterparts.

These findings are consistent with other evidence, in both animals and humans, indicating that prenatal exposure to the biological consequences of severe maternal stress can induce epigenetic changes, through methylation, that impair functioning of the body’s stress response system (Daskalakis & Yehuda, 2014; Mueller & Bale, 2008). In the Tutsi mothers and children, the effects of genocidal trauma were long-lasting, evident in serious psychological disorders nearly two decades later.

This Rwandan mother gave birth shortly after the Tutsi genocide. Nine years later, she continues to suffer from PTSD caused by first-hand experience of atrocities, including repeated rape and loss of her mother, brother, and two sisters in the massacre. Her daughter’s PTSD and depression might be the result of prenatal exposure to severe maternal stress, which can trigger epigenetic changes that disrupt the body’s stress response system.


As the researchers noted, more remains to be discovered about exactly how maternal trauma exposure compromised the Tutsi children’s capacity to manage stress. Epigenetic processes, not just prenatally but also at later ages, may have been largely responsible. Alternatively, poor-quality parenting, resulting from maternal anxiety, irritability, anger, and depression, could have been the major influence. More likely, epigenetic changes, inept parenting, and other unfavorable environmental influences combined to place the Tutsi children at high risk for PTSD and depression. In Chapter 3, we will return to the impact of prenatal stress, including evidence showing that its negative impact can be lessened or prevented through social support.

Epigenetics is still an emerging field, and clarifying its mechanisms may prove to be even more complex than efforts to understand DNA sequence variations. But from what we already know, one lesson is clear: Development is best understood as a series of complex exchanges between genes and the child’s multi-layered, surrounding environment. In this way, epigenesis is consistent with the developmental systems perspective, introduced on page 11 in Chapter 1 (Bjorklund & Ellis, 2014). Although people cannot be changed in any way we might desire, environments can modify genetic influences. The success of any attempt to improve development depends on the characteristics we want to change, the genetic makeup of the individual, and the type and timing of our intervention.

Ask Yourself

Connect ■ Explain how each of the following concepts supports the conclusion that genetic influences on human characteristics are not constant but change over time: somatic mutation (page 57), niche-picking (page 81), and epigenesis (page 82).

Apply ■ Bianca’s parents are accomplished musicians. At age 4, Bianca began taking piano lessons. By age 10, she was accompanying the school choir. At age 14, she asked to attend a special music high school. Explain how gene–environment correlation promoted Bianca’s talent.

Reflect ■ What aspects of your own development—for example, interests, hobbies, college major, or vocational choice—are probably due to niche-picking? Explain.


2.1 Genetic Foundations (p. 51)

2.1a Explain what genes are and how they are transmitted from one generation to the next.

Each individual’s phenotype, or observable characteristics, is a product of both genotype and environment. Chromosomes, rodlike structures within the cell nucleus, contain our hereditary endowment. Along their length are genes, segments of deoxyribonucleic acid (DNA).

Protein-coding genes directly affect our body’s characteristics. Regulator genes modify protein-coding genes’ instructions. Environmental factors also alter gene expression.

Gametes, or sex cells, result from a cell division process called meiosis, which ensures that each individual receives a unique set of genes from each parent. Once sperm and ovum unite, the resulting zygote will then have a full complement of chromosomes.

Genetic sex is determined by whether sperm containing an X-bearing or a Y-bearing chromosome fertilizes the ovum.

Fraternal, or dizygotic, twins result when two ova are released from the mother’s ovaries and each is fertilized. Identical, or monozygotic, twins develop when a zygote divides in two during the early stages of cell duplication.

2.1b Describe various patterns of gene–gene interaction.

Traits controlled by single genes follow dominant–recessive and incomplete-dominance inheritance. Homozygous individuals have two identical alleles, or forms of a gene. Heterozygous individuals, with one dominant and one recessive allele, are carriers of the recessive trait. In incomplete dominance, both alleles are expressed in the phenotype.

X-linked inheritance applies when recessive disorders are carried on the X chromosome and, therefore, are more likely to affect males.

In genomic imprinting, alleles are chemically marked within the ovum or sperm, silencing one pair member and leaving the other to be expressed, regardless of its makeup.

Harmful genes arise from mutation, which can occur spontaneously or be caused by hazardous environmental agents. Germline mutation occurs in the cells that give rise to gametes; somatic mutation can occur in body cells at any time of life.

Traits that vary on a continuum, such as intelligence and personality, result from polygenic inheritance—the effects of many genes.

2.1c Describe major chromosomal abnormalities, and explain how they occur.

Most chromosomal abnormalities result from errors during meiosis. The most common, Down syndrome, leads to intellectual disability, distinctive physical features, and physical defects. Sex chromosome disorders are milder than defects of the autosomes.

2.2 Reproductive Choices (p. 59)

2.2 Discuss counseling, medical procedures, and reproductive options that can assist prospective parents in having healthy children.

Genetic counseling helps couples consider reproductive options when they are at risk for giving birth to children with genetic abnormalities. Prenatal diagnostic methods allow early detection of developmental problems. Advances in fetal medicine and genetic engineering offer hope for treating hereditary disorders.

Reproductive technologies, such as donor insemination, in vitro fertilization, and surrogate motherhood, enable individuals to conceive children who otherwise would not. However, the technologies raise legal and ethical concerns.

Many adults who cannot conceive or who are likely to transmit a genetic disorder choose adoption. Although adopted children tend to have more learning and emotional problems than children in general, most fare well in the long run. Warm, supportive parenting that includes open communication about adoption contributes to favorable development.

2.3 Environmental Contexts for Development (p. 65)

2.3 Discuss aspects of children’s multi-layered environment that influence their development and well-being.

In the family—the first and most enduring context for development—the behaviors of each member affect those of the others in a dynamic, ever-changing system of direct and indirect influences. Warm, gratifying family ties, which foster effective coparenting, help ensure children’s psychological health.

Socioeconomic status (SES) profoundly affects family functioning and children’s development. Higher-SES parents tend to have smaller families, to value independence, and to engage in warm, verbally stimulating interaction with children. Lower-SES parents tend to value obedience and to use more commands, criticism, and physical punishment.

In affluent families, parental physical and emotional unavailability may impair youths’ adjustment. Poverty and homelessness undermine effective parenting and pose serious threats to children’s development.

Children benefit from supportive ties between the family and community, including stable, socially cohesive neighborhoods that provide constructive leisure and enrichment activities. High-quality schooling and parent involvement in children’s education enhance academic achievement, educational attainment, and life chances.

The values and practices of cultures and subcultures affect all aspects of children’s daily life. Extended families, common among many ethnic minorities, help protect family members from the negative effects of poverty and other stressful life conditions. The Hispanic cultural value of familism, which elevates family needs above individual concerns, is associated with multiple positive developmental outcomes.

Cross-national differences in collectivism–individualism powerfully affect public policies aimed at addressing social problems. Largely because of its strongly individualistic values, the United States lags behind other developed nations in policies safeguarding children and youths.

2.4 Understanding the Relationship Between Heredity and Environment (p. 78)

2.4 Explain the various ways heredity and environment may combine to influence complex traits.

Behavioral genetics examines the contributions of nature and nurture to diversity in human traits and abilities. Heritability estimates, derived from kinship studies, attempt to quantify the influence of genetic factors on such complex traits as intelligence and personality. However, the accuracy of this approach has been challenged.

In gene–environment interaction, heredity influences each individual’s responsiveness to qualities of the environment. In gene–environment correlation, children’s genes affect the environments to which they are exposed, at first passively and evocatively. At older ages, children actively choose environments that complement their heredity, a process called niche-picking.

Epigenesis reminds us that development is best understood as a series of complex, bidirectional exchanges between heredity and all levels of the environment. Epigenetic research is uncovering biochemical processes—such as methylation—through which the environment can modify gene expression.


allele (p. 54)

autosomes (p. 53)

behavioral genetics (p. 78)

carrier (p. 55)

chromosomes (p. 51)

coparenting (p. 66)

deoxyribonucleic acid (DNA) (p. 51)

dominant–recessive inheritance (p. 55)

epigenesis (p. 82)

familism (p. 75)

fraternal, or dizygotic, twins (p. 53)

gametes (p. 53)

gene (p. 52)

gene–environment correlation (p. 80)

gene–environment interaction (p. 80)

genetic counseling (p. 60)

genomic imprinting (p. 57)

genotype (p. 51)

heritability estimate (p. 78)

heterozygous (p. 54)

homozygous (p. 54)

identical, or monozygotic, twins (p. 54)

incomplete dominance (p. 55)

kinship studies (p. 78)

meiosis (p. 53)

methylation (p. 82)

mutation (p. 57)

niche-picking (p. 81)

phenotype (p. 51)

polygenic inheritance (p. 58)

prenatal diagnostic methods (p. 62)

protein-coding genes (p. 52)

public policies (p. 76)

regulator genes (p. 52)

sex chromosomes (p. 53)

socioeconomic status (SES) (p. 67)

subculture (p. 74)

X-linked inheritance (p. 56)

zygote (p. 53)

Descriptions of Images and Figures

Back to Figure

At the center of the cell is the nucleus, where the chromosomes are located. These chromosomes were used to create the karyotype, which shows 23 distinct pairs of chromosomes.

Back to Figure

At the top of the diagram are the carrier father and carrier mother, each labeled Np. Below are 4 children, a normal son labeled NN, a carrier daughter labeled Np, another carrier daughter labeled Np, and a PKU son labeled pp.

Back to Figure

At the top of the diagram are a normal father labeled XY and a carrier mother labeled XX. One X is circled and labeled as follows: this X chromosome has one abnormal recessive allele. Below are 4 children, a normal female labeled XX, a normal male labeled XY, a carrier female labeled XX, with 1 X circled, and an affected male, labeled XY, with the X circled.

Back to Figure

The x-axis is labeled maternal age in years, and the y-axis is labeled incidence per 1,000 births. The data for Down syndrome specifically is as follows. Age 20, 1 in 1,770. Age 35: 1 in 400. Age 40: 1 in 100. Age 45: 1 in 30. Age 50: 1 in 11. The data for all chromosomal abnormalities is as follows. Age 20: 1 in 1,525. Age 35: 1 in 200. Age 40: 1 in 65. Age 45: 1 in 20. Age 50: 1 in 7.

Back to Figure

The data shows that children who do not eat dinner with their parents have a significantly higher risk of developing anxiety and depression, delinquency and substance abuse, and poor school grades than children who do eat dinner with their parents.

Back to Figure

The data is as follows.

• United States: 20

• Lithuania: 19

• Greece: 18.5

• Canada: 16.5

• Portugal: 16

• Slovakia: 15

• Poland: 13

• Latvia: 12

• Estonia: 12

• France: 11.5

• Belgium: 11

• United Kingdom: 11

• Czech Republic: 10.5

• Netherlands: 10.5

• Austria: 9.5

• Sweden: 9

• Norway: 7.5

• South Korea: 7.5

• Slovenia: 7

• Finland: 4

All values are estimated.

Back to Figure

The x-axis is labeled quality of environment with an arrow pointing from left to right, the left labeled extremely unstimulating and the right labeled highly enriched. The y axis is labeled intelligence scores and ranges from 0 to 150. The graph shows 3 curves. The first is labeled Ben and rises linearly from about 50 to 130 from left to right. The second is labeled Linda and it starts at about 50, rises to about 140, and then falls to about 110. The last curve is labeled Ron and it starts at about 60, falls to about 30, and then rises almost linearly to about 125.

Back to Figure

Three rings surround a person. The rings are labeled gene expression, behavior, and environment, which consists of home, neighborhood, school, and community. Arrows labeled bidirectional changes point between the rings. An arrow below the rings points in one direction and is labeled individual development.

Back to Figure

The mean extent of GR methylation, by person, is as follows.

• Trauma-exposed mothers: 6.5

• Children of trauma-exposed mothers: 9.5

• Non-exposed mothers: 5.

• Children of non-exposed mothers: 5.5.

All values are estimated.


Giving Birth to Peace

Lotfeh Mohamed El Mari, 11 years, Lebanon

Expectant mothers hope that their nearly full-term fetuses will benefit from and eventually contribute to a world of peace. How is the one-celled organism transformed into a baby with the capacity to participate in family life? What factors support or undermine this earliest period of development? Chapter 3 provides answers to these questions.

Reprinted with permission from The International Child Art Foundation, Washington, DC


3.1 Motivations for Parenthood

Why Have Children? • How Large a Family? • Is There a Best Time During Adulthood to Have a Child?

3.2 Prenatal Development

Conception • Germinal Period • Period of the Embryo • Period of the Fetus

3.3 Prenatal Environmental Influences

Teratogens • Other Maternal Factors

■ Biology and Environment: Self-Regulation Therapy for Children with Fetal Alcohol Spectrum Disorder (FASD)

■ Social Issues: Health: The Nurse–Family Partnership: Reducing Maternal Stress and Enhancing Child Development Through Social Support

3.4 The Importance of Prenatal Health Care

■ Cultural Influences: Culturally Sensitive Prenatal Health Care: Perspectives of Expectant Mothers

One fall, Yolanda and Jay enrolled in an evening section of my child development course, when Yolanda was just two months pregnant. In their early thirties, married for several years, and their careers well under way, they had decided to have a baby. Each week, they arrived for class full of questions: “How does the baby grow before birth?” “When is each organ formed?” “Has its heart begun to beat?” “Can it hear, feel, or sense our presence?”

Most of all, Yolanda and Jay wanted to do everything possible to make sure their baby would be born healthy. Yolanda started to wonder about her diet and whether she should keep up her daily aerobic workouts. And she asked whether an aspirin for a headache, a glass of wine at dinner, or a few cups of coffee during the workday might be harmful.

In this chapter, we answer Yolanda and Jay’s questions, along with a great many more that researchers have asked about the events before birth. We begin our discussion with these puzzling questions: Why is it that generation after generation, most couples want to become parents? And what factors influence their decision to have just one child or more than one?

Then we trace prenatal development, addressing both supports for healthy growth and damaging influences that threaten the child’s health and survival. Because the changes taking place during these nine months are so astounding, the prenatal environment can exert a powerful, lasting impact—for better or for worse—on physical and mental health. ■


3.1 Discuss factors that contribute to contemporary adults’ decision making about parenthood, including timing of childbearing and family size.

What, in your view, are the benefits and drawbacks of having children? How large would your ideal family be, and why? Until just a few decades ago, the issue of whether to have children was, for many adults, a biological given or a compelling social expectation. Today, in Western industrialized nations, it is a matter of true individual choice. Effective contraception enables sexually active adults to avoid having children in most instances. And changing cultural values allow people to remain childless with far less fear of social criticism than a generation or two ago.

Nevertheless, the 6 percent of American 18- to 40-year-olds who currently say they do not want children is just slightly higher than the 5 percent who said so three decades ago. The desire for children remains the norm: In a survey of a large, nationally representative sample of U.S. adults of childbearing age, 90 percent said they already have children or are planning to have them (Gallup, 2013). Actually becoming parents, however, is affected by a complex array of contextual factors, including financial circumstances, religious values, partnership changes, career goals, health conditions, and availability of supportive government and workplace family policies (Mills et al., 2011; Vespa, 2017).

3.1.1 Why Have Children?

In addition to the contextual factors just mentioned, vital personal attributes called childbearing motivations—positive or negative inclinations toward the idea of parenthood—affect people’s decision to have children as well as their psychological adjustment to pregnancy and a baby’s arrival. In Western nations, these motivations have changed over time, increasingly emphasizing individual fulfillment and deemphasizing obligation to society (Frejka et al., 2008; Guedes et al., 2015).

Advantages and Disadvantages of Parenthood Mentioned by American and European Adults of Childbearing Age (in General Order of Importance)

When Americans and Europeans are asked about their childbearing motivations, they mention a variety of advantages and disadvantages, listed in Table 3.1. Although some ethnic and regional differences exist, in all groups highly rated reasons for having children include personal fulfillment—for example, the warm, affectionate relationship and opportunities for care and teaching that children provide. Also frequently mentioned are the deepening of a couple’s relationship that comes from sharing in a challenging but important life task, and the sense of future continuity that results from perpetuating a family line and passing on one’s heritage and values (Guedes, et al., 2015). Less important but still mentioned are social and economic returns, including being recognized as a family and having children to rely on as sources of caregiving and financial support late in life.

Table 3.1 Advantages anddbearing Age (in General Order of Importance)



Giving and receiving warmth and affection and providing care and teaching

Enhancing life’s meaning

Nurturing a new person and personality

Creating one’s own family

Strengthening the couple relationship through a shared project

Fulfilling a partner’s desire for parenthood

Carrying on one’s family name, lineage, heritage, or values

Being accepted as a responsible and mature member of the community

Having a source of caregiving and economic support in later life

Risk of birth complications

Constant worries over and responsibility for children’s health, safety, and well-being

Fear that children will turn out badly, through no fault of one’s own

Role overload—not enough time to meet both child-rearing and job responsibilities

Risks of bringing up children in a world plagued by crime, war, and pollution

Financial strain and sacrifices

Reduced time to spend with partner

Loss of privacy

Sources: Guedes, et al., 2015; Miller, 2009.

Most adults also realize that having children means years of extra burdens and responsibilities. Among disadvantages of parenthood, they often cite risk of birth complications; constant worries over children’s health, safety, and well-being; fear that children will turn out badly; concerns about role overload (not enough time for both family and work responsibilities); and worries about bringing up children in a troubled world. The financial strains and sacrifices of child rearing also rank high. According to a conservative estimate, middle-income parents in the United States today will spend nearly $300,000 to rear a child from birth to age 18, and many will incur substantial additional expense for higher education (U.S. Department of Agriculture, 2017).

Look and Listen

Interview several parents of infants or preschoolers about the benefits and challenges of parenthood. Ask which issues they considered before starting a family. How deliberate about family planning were they?

Greater freedom to choose whether, when, and how to have children (see the discussion of reproductive choices in Chapter 2) makes contemporary family planning more challenging, as well as intentional, than in past generations. Still, about 30 percent of U.S. births are the result of unintended pregnancies, with most born to low-income, less educated mothers—circumstances associated with delayed prenatal care, premature birth, and child health problems (Bearak et al., 2018). Yet opportunities to explore childbearing motivations in high school, college, and community-based health education classes and through family-planning counseling might encourage more adults to make informed and personally meaningful decisions—a trend that would increase the chances that they would have children when ready, find parenting an enriching experience, and rear physically and mentally healthy children.

Among often-cited reasons for having children are the affectionate relationship and opportunity for care and teaching that a child provides.

Axel Bernstorff/Cultura Creative RF/Alamy Stock Photo

3.1.2 How Large a Family?

Prior to the economic recession of 2007–2009, the overall fertility rate, or lifetime births per woman, in developed countries was about 2.1. Since then, the U.S. fertility rate has declined by 16 percent, to 1.8. Fertility rates are similar, or even lower, in other industrialized nations: 1.9 in Sweden, 1.8 in Australia and the United Kingdom, 1.6 in Canada, 1.5 in Germany, 1.4 in Italy and Japan, and 1.3 in Spain (World Bank, 2018b).

A major reason for this drop in births is that increasing numbers of adults of childbearing age are delaying marriage and parenthood until their education is complete, their work lives are under way, and they are more secure economically (Vespa, 2017). As Figure 3.1 shows, the U.S. birthrate decline is substantial for women in their twenties, with small gains in births limited to women ages 35 and older (Centers for Disease Control and Prevention, 2018f; Pew Research Center, 2018e). Starting a family later is associated with having fewer children.

Average family size has declined in recent decades in most industrialized nations. But, contrary to popular belief, having more children does not reduce the intelligence or life chances of later-born children.


A smaller family size is compatible with the decision of increasing numbers of women to divide their energies between family and career. In addition, popular advice to prospective parents often includes limiting family size in the interests of “child-rearing quality,” based on the presumed ability of parents of fewer children to devote more affection, stimulation, and material resources to each child, thus enhancing the intellectual development of all. Do smaller families really make brighter children, as is commonly believed?

For years, researchers thought that earlier birth order and wider spacing might grant children more parental involvement and, therefore, result in more favorable cognitive outcomes. But two decades of research consistently indicates that the relationship of birth order and spacing to children’s intelligence is negligible (Damian & Roberts, 2015; Kanazawa, 2012; Rodgers et al., 2000; Wichman, Rodgers, & MacCallum, 2007). Rather, parents’ differential treatment of siblings is far more responsive to children’s personalities, interests, and behaviors than to these aspects of family structure.

Figure 3.1 Births to U.S. women by age in 2007 and 2017. Births declined for women in their twenties through mid-thirties while increasing for women 35 and older, reflecting the trend toward delayed parenthood. (Based on Centers for Disease Control and Prevention, 2018f.)

Furthermore, the well-documented association between large family size and lower intelligence test scores of all siblings can be entirely explained by a strong trend for low-SES mothers to give birth to more children. Most of these families suffer from poverty, which threatens all domains of development (see pages 70–71 in Chapter 2). Among children of well-educated, economically advantaged mothers, the family size–intelligence relationship disappears (Guo & VanWey, 1999; Wichman, Rodgers, & MacCallum, 2007). In sum, although many good reasons exist for limiting family size, the concern that additional births will reduce parenting quality and thus impair children’s skills and life chances is not warranted.

3.1.3 Is There a Best Time During Adulthood to Have a Child?

Yolanda, at age 32, is pregnant for the first time. Many people believe that women should, ideally, have children before 35 because the risk of having a baby with a chromosomal disorder rises sharply from then on. Advanced paternal age is associated with elevated risk of certain genetically influenced disorders as well (see page 60 in Chapter 2).

Reproductive capacity also declines with age. Between ages 25 and 34, 12 percent of women are affected, a figure that escalates to 39 percent for 35- to 39-year-olds and to 47 percent for 40- to 44-year-olds. Similarly, age affects male reproductive capacity. Amount of semen, concentration of sperm in each ejaculation, and quality of sperm decline gradually after age 35 (Chandra, Copen, & Stephen, 2013).

Highly educated women with demanding careers are especially likely to delay parenthood (Pew Research Center, 2015a). Many believe, incorrectly, that if they have difficulty conceiving, they can rely on reproductive technologies. But recall from Chapter 2 that the success of these procedures declines steadily with age. Although no one time during adulthood is best to begin parenthood, individuals who decide to put off pregnancy until their late thirties or early forties risk having fewer biological children than they desire or none at all.


3.2 List the three periods of prenatal development, and describe the major milestones of each.

The sperm and ovum that unite to form the new individual are uniquely suited for the task of reproduction. The ovum is a tiny sphere, measuring 1⁄175 inch in diameter—barely visible to the naked eye as a dot the size of the period at the end of this sentence. But in its microscopic world, it is a giant—the largest cell in the human body, making it a perfect target for the much smaller sperm, which measure only 1⁄500 inch.

3.2.1 Conception

About once every 28 days, in the middle of a woman’s menstrual cycle, an ovum bursts from one of her ovaries, two walnut-sized organs located deep inside her abdomen, and is drawn into one of two fallopian tubes—long, thin structures that lead to the hollow, softly lined uterus (see Figure 3.2). While the ovum is traveling, the spot on the ovary from which it was released, now called the corpus luteum, secretes hormones that prepare the lining of the uterus to receive a fertilized ovum. If pregnancy does not occur, the corpus luteum shrinks, and the lining of the uterus is discarded two weeks later with menstruation.

Conception. In this photo, taken with the aid of a powerful microscope, sperm penetrate the surface of the ovum, the largest cell in the human body. When one sperm succeeds in fertilizing the ovum, the resulting zygote begins to duplicate.


The male produces sperm in vast numbers—an average of 300 million a day—in the testes, two glands located in the scrotum, sacs that lie just behind the penis. In the final process of maturation, each sperm develops a tail that permits it to swim long distances, upstream in the female reproductive tract, through the cervix (opening of the uterus) and into the fallopian tube, where fertilization usually takes place. The journey is difficult, and many sperm die. Only 300 to 500 reach their destination. Once in the fallopian tube, sperm live for up to six days and can lie in wait for the ovum, which survives for only one day after its release from the ovary. However, most conceptions result from intercourse occurring during a three-day period—on the day of ovulation or during the two days preceding it (Mu & Fehring, 2014).

Figure 3.2 Female reproductive organs, showing fertilization, early cell duplication, and implantation. (From Before We Are Born, 9th ed., by K. L. Moore, T. V. N. Persaud, & M G. Torchia, p. 33. Copyright © 2016, adapted with permission from Elsevier, Inc.)

With conception, the story of prenatal development begins to unfold. The vast changes that take place during the 38 weeks of pregnancy are usually divided into three periods: (1) the germinal period, (2) the period of the embryo, and (3) the period of the fetus. As we consider each, you may find it useful to refer to Table 3.2 on page 92, which summarizes milestones of prenatal development.

3.2.2 Germinal Period

The germinal period lasts about two weeks, from fertilization and formation of the zygote until the tiny mass of cells drifts down and out of the fallopian tube and attaches itself to the wall of the uterus. The zygote’s first cell duplication is long and drawn out, taking about 30 hours. Gradually, new cells are added at a faster rate, forming a hollow, fluid-filled ball called a blastocyst that by the fourth day consists of 60 to 70 cells (refer again to Figure 3.2). The cells on the inside of the blastocyst, called the embryonic disk, will become the new organism; the outer ring of cells, termed the trophoblast, will become the structures that provide protective covering and nourishment.


Between the seventh and ninth days, implantation occurs: The blastocyst burrows deep into the uterine lining. Surrounded by the woman’s nourishing blood, it starts to grow in earnest. At first, the trophoblast (protective outer layer) multiplies fastest. It forms a membrane, called the amnion, that encloses the developing organism in amniotic fluid, which helps keep the temperature of the prenatal world constant and provides a cushion against any jolts caused by the woman’s movement. A yolk sac emerges that produces blood cells until the developing liver, spleen, and bone marrow are mature enough to take over this function (Moore, Persaud, & Torchia, 2016).

Table 3.2 Milestones of Prenatal Development


Prenatal Period


Length and Weight

Major Events






The one-celled zygote multiplies and forms a blastocyst.

The blastocyst burrows into the uterine lining. Structures that feed and protect the developing organism begin to form—amnion, chorion, yolk sac, placenta, and umbilical cord.




¼ inch (6 mm)

1 inch (2.5 cm); 1/7ounce (4 g)

A primitive brain and spinal cord appear. Heart, muscles, ribs, backbone, and digestive tract begin to develop.

Many external body structures (face, arms, legs, toes, fingers) and internal organs form, and production and migration of neurons in the brain begin. The sense of touch starts to develop, and the embryo can move.



3 inches (7.6 cm); less than 1 ounce (28 g)

Rapid increase in size begins. Nervous system, organs, and muscles become organized and connected, touch sensitivity extends to most of the body, and new behavioral capacities (kicking, thumb sucking, mouth opening, and rehearsal of breathing) appear. External genitals are well-formed, and the fetus’s sex is evident.



12 inches (30 cm); 1.8 pounds (820 g)

The fetus continues to enlarge rapidly. In the middle of this period, the mother can feel fetal movements. Vernix and lanugo keep the fetus’s skin from chapping in the amniotic fluid. Most of the brain’s neurons are in place by 24 weeks. Eyes are sensitive to light, and the fetus reacts to sound.



20 inches (50 cm); 7.5 pounds (3,400 g)

The fetus has a good chance of survival if born during this time. Size increases. Lungs mature. Rapid brain development, in neural connectivity and organization, enables sensory and behavioral capacities to expand. In the middle of this period, a layer of fat is added under the skin. Antibodies are transmitted from mother to fetus to protect against disease. Most fetuses rotate into an upside-down position in preparation for birth.

Sources: Moore, Persaud, & Torchia, 2016.

Photos (from top to bottom): © Claude Cortier/Science Source; © Dr. G. Moscoso/Science Source; © Claude Edelmann/Science Source; © James Stevenson/Science Source; © LENNART NILSSON, TT / SCIENCE PHOTO

The events of these first two weeks are delicate and uncertain. As many as 30 percent of zygotes do not survive this period. In some, the sperm and ovum do not join properly. In others, cell duplication never begins. By preventing implantation in these cases, nature eliminates most prenatal abnormalities (Sadler, 2014).

The Placenta and Umbilical Cord

By the end of the second week, cells of the trophoblast form another protective membrane—the chorion, which surrounds the amnion. From the chorion, tiny fingerlike villi, or blood vessels, emerge.1 As these villi burrow into the uterine wall, the placenta starts to develop. By bringing the embryo’s and mother’s blood close together, the placenta permits food and oxygen to reach the developing organism and waste products to be carried away. A membrane forms that allows these substances to be exchanged but prevents the mother’s and embryo’s blood from mixing directly (see Figure 3.3).

1 Recall from Table 2.2 on page 62 that chorionic villus sampling is the prenatal diagnostic method that can be performed earliest, at nine weeks after conception.

The placenta is connected to the developing organism by the umbilical cord, which first appears as a primitive body stalk and, during the course of pregnancy, grows to a length of 1 to 3 feet. The umbilical cord contains one large vein that delivers blood loaded with nutrients and two arteries that remove waste products. The force of blood flowing through the cord keeps it firm, so it seldom tangles while the embryo, like a space-walking astronaut, floats freely in its fluid-filled chamber (Moore, Persaud, & Torchia, 2016). By the end of the germinal period, the developing organism has found food and shelter.

Germinal period: seventh to ninth day. The fertilized ovum duplicates at an increasingly rapid rate, forming a hollow ball of cells, or blastocyst, by the fourth day after conception. Between the seventh and ninth day the blastocyst, as shown here magnified thousands of times, burrows into the uterine lining.


3.2.3 Period of the Embryo

The period of the embryo lasts from implantation through the eighth week of pregnancy. During these brief six weeks, the most rapid prenatal changes take place as the groundwork is laid for all body structures and internal organs. Because all parts of the body are forming, the embryo is especially vulnerable to interference with healthy development. But the short time span of embryonic growth helps limit opportunities for serious harm.

Last Half of the First Month

In the first week of this period, the embryonic disk forms three layers of cells: (1) the ectoderm, which will become the nervous system and skin; (2) the mesoderm, which will develop into the muscles, skeleton, circulatory system, and other internal organs; and (3) the endoderm, which will become the digestive system, lungs, urinary tract, and glands. These three layers give rise to all parts of the body.

Figure 3.3 Cross-section of the uterus, showing detail of the placenta. The embryo’s blood flows from the umbilical cord arteries into the chorionic villi and returns via the umbilical cord vein. The mother’s blood circulates in spaces surrounding the chorionic villi. A membrane between the two blood supplies permits food and oxygen to be delivered and waste products to be carried away. The two blood supplies do not mix directly. The umbilical arteries carry oxygen-poor blood (shown in blue) to the placenta, and the umbilical vein carries oxygen-rich blood (shown in red) to the fetus. (Adapted from Before We Are Born, 9th ed., by K. L. Moore, T. V. N. Persaud, & M. G. Torchia, p. 76. Copyright © 2016, reprinted with permission from Elsevier, Inc.)

At first, the nervous system develops fastest. The ectoderm folds over to form the neural tube, or primitive spinal cord. At 3½ weeks, the top swells to form the brain. While the nervous system is developing, the heart begins to pump blood, and muscles, backbone, ribs, and digestive tract appear. At the end of the first month, the curled embryo—only ¼ inch long—consists of millions of organized groups of cells with specific functions.

The Second Month

In the second month, growth continues rapidly. The eyes, ears, nose, jaw, and neck form. Tiny buds become arms, legs, fingers, and toes. Internal organs are more distinct: The intestines grow, the heart develops separate chambers, and the liver and spleen take over production of blood cells so that the yolk sac is no longer needed. Changing body proportions cause the embryo’s posture to become more upright.

Period of the embryo: fourth week. This 4-week-old embryo is only ¼-inch long, but many body structures have begun to form.


During the fifth week, production of neurons (nerve cells that store and transmit information) begins deep inside the neural tube at the astounding pace of more than 250,000 per minute (Jabès & Nelson, 2014). Once formed, neurons begin traveling along tiny threads to their permanent locations, where they will form the major parts of the brain.

By 8 weeks, the testes in the male start to develop and begin secreting the hormone testosterone, which will stimulate differentiation of male internal reproductive organs and the penis and scrotum during the coming month. In the absence of testosterone, female reproductive organs form.

By the end of this period, the embryo—about 1 inch long and 1/7 ounce in weight—can already sense its world. It responds to touch, particularly in the mouth area and on the soles of the feet. And it can move, although its tiny flutters are still too light to be felt by the mother (Moore, Persaud, & Torchia, 2016).

3.2.4 Period of the Fetus

The period of the fetus, from the ninth week to the end of pregnancy, is the longest prenatal period. During this “growth and finishing” phase, the organism increases rapidly in size.

The Third Month

In the third month, the organs, muscles, and nervous system start to become organized and connected. Touch sensitivity extends to most of the body (Hepper, 2015). When the brain signals, the fetus kicks, bends its arms, forms a fist, curls its toes, turns its head, opens its mouth, and even sucks its thumb, stretches, and yawns. The tiny lungs begin to expand and contract in an early rehearsal of breathing movements.

By the twelfth week, the external genitals are well-formed, and the sex of the fetus can be detected with ultrasound (Sadler, 2014). Other finishing touches appear, such as fingernails, toenails, tooth buds, and eyelids. The heartbeat can now be heard through a stethoscope.

Period of the embryo: seventh week. The embryo’s posture is more upright. Body structures—eyes, nose, arms, legs, and internal organs—are more distinct. The embryo now responds to touch and can also move. At less than one inch long and an ounce in weight, it is still too tiny to be felt by the mother.


Prenatal development is sometimes divided into trimesters, or three equal time periods. At the end of the third month, the first trimester is complete.

The Second Trimester

By the middle of the second trimester, between 17 and 20 weeks, the new being has grown large enough that the mother can feel its movements. Already, the fetus is remarkably active—in motion nearly 30 percent of the time—which helps strengthen the joints and muscles (DiPietro, Costigan, & Voegtline, 2015). A white, cheeselike substance called vernix emerges on the skin, protecting it from chapping during the long months spent bathing in the amniotic fluid. White, downy hair called lanugo also appears over the entire body, helping the vernix stick to the skin.

At the end of the second trimester, many organs are well-developed. And most of the brain’s billions of neurons are in place; few will be produced after this time. However, glial cells, which support and feed the neurons, continue to increase rapidly throughout the remaining months of pregnancy, as well as after birth. Consequently, brain weight increases tenfold from the twentieth week until birth (Roelfsema et al., 2004). At the same time, neurons begin forming synapses, or connections, at a rapid pace.

Period of the fetus: eleventh week. The brain and muscles of the rapidly growing fetus are better connected. The fetus can kick, bend its arms, open and close its hands and mouth, and suck its thumb. The yolk sac shrinks as the internal organs assume blood cell production.


Brain growth means new sensory and behavioral capacities. The 20-week-old fetus can be stimulated as well as irritated by sounds. And if a doctor looks inside the uterus using fetoscopy (see Table 2.2 on page 62), fetuses try to shield their eyes from the light with their hands, indicating that sight has begun to emerge (Moore, Persaud, & Torchia, 2016). Still, a fetus born at this time cannot survive. Its lungs are immature, and the brain cannot yet control breathing movements or body temperature.

The Third Trimester

During the final trimester, a fetus born early has a chance for survival. The point at which the baby can first survive, called the age of viability, occurs sometime between 22 and 26 weeks (Moore, Persaud, & Torchia, 2016). A baby born between the seventh and eighth months, however, usually needs oxygen assistance to breathe. Although the brain’s respiratory center is now mature, tiny air sacs in the lungs are not yet ready to inflate and exchange carbon dioxide for oxygen.

The brain continues to make great strides. The cerebral cortex, the seat of human intelligence, enlarges. Convolutions and grooves in its surface appear, permitting a dramatic increase in surface area that allows for maximum prenatal brain growth without the full-term baby’s head becoming too large to pass through the birth canal. Brain-imaging evidence reveals rapid gains in fetal neural organization: At first, neural connectivity increases within brain areas supporting specific functions, such as vision, movement, language, and integration of information. In the last six weeks, connections begin to form between these areas, yielding primitive brain networks (Thomason et al., 2014). This pattern of brain growth, which supports coordinated processing of information, will continue after birth.

Period of the fetus: twenty-second week. This fetus is almost 1 foot long and weighs slightly more than 1 pound. Its movements can be felt readily by the mother and by others who touch her abdomen. If born now, the fetus would have a slim chance of surviving.


As neural organization improves, the fetus spends more time awake. At 20 weeks, fetal heart rate reveals no periods of alertness. But by 28 weeks, fetuses are awake about 11 percent of the time, a figure that rises to 16 percent just before birth (DiPietro et al., 1996). Between 30 and 34 weeks, fetuses show rhythmic alternations between sleep and wakefulness that gradually increase in organization (Rivkees, 2003). Around 36 weeks, synchrony between fetal heart rate and motor activity peaks: A rise in heart rate is usually followed within five seconds by a burst of motor activity (DiPietro et al., 2006; DiPietro, Costigan, & Voegtline, 2015). These are clear signs that functioning brain networks have started to take shape in the brain.

By the end of pregnancy, the fetus takes on the beginnings of a personality. Fetal activity is linked to infant temperament. In one study, more active fetuses during the third trimester became 1-year-olds who could better handle frustration and 2-year-olds who were more active as well as less fearful, in that they more readily interacted with toys and with an unfamiliar adult in a laboratory (DiPietro et al., 2002). Perhaps fetal activity is an indicator of healthy neurological development, which fosters adaptability in childhood. The relationships just described, however, are modest. As we will see in Chapter 6, sensitive caregiving can modify the temperaments of children who have difficulty adapting to new experiences.

The third trimester brings greater responsiveness to external stimulation. As we will see when we discuss newborn capacities in Chapter 4, fetuses acquire taste and odor preferences from bathing in and swallowing amniotic fluid (its makeup is influenced by the mother’s diet). Between 23 and 30 weeks, the fetus is clearly sensitive to pain, so painkillers should be used in any surgical procedures (Lee et al., 2005). Around 29 weeks, fetuses can hear. When presented with a repeated auditory stimulus against the mother’s abdomen, they initially react with a rise in heart rate, brain-wave activity, and body movements (Kisilevsky, 2016). Then responsiveness gradually declines, indicating habituation (adaptation) to the sound. If a new auditory stimulus is introduced, heart rate and brain waves recover to a high level, revealing that the fetus recognizes the new sound as distinct from the original stimulus (Hepper, Dornan, & Lynch, 2012; Muenssinger et al., 2013). This indicates that fetuses can remember for at least a brief period.

Within the next six weeks, fetuses distinguish the tone and rhythm of different voices and sounds—learning that will serve as a springboard for language development. In various studies, they showed systematic heart-rate and brain-wave changes in response to the mother’s voice versus the father’s or a stranger’s, to their native language (English) versus a foreign language (Mandarin Chinese), and to a simple familiar melody (descending tones) versus an unfamiliar melody (ascending tones) (Granier-Deferre et al., 2003; Kisilevsky & Hains, 2011; Kisilevsky et al., 2009; Lecanuet et al., 1993; Lee & Kisilevsky, 2013; Voegtline et al., 2013). In one clever investigation, mothers read aloud Dr. Seuss’s lively book The Cat in the Hat each day during the last six weeks of pregnancy. After birth, their infants learned to turn on recordings of the mother’s voice by sucking on nipples (DeCasper & Spence, 1986). They sucked hardest to hear The Cat in the Hat—the sound they had come to know while still in the womb.

On the basis of these findings, would you recommend that expectant mothers provide fetuses with stimulation aimed at enhancing later development? Although specific forms of fetal stimulation, such as reading aloud, contribute to development in the short-term, they are unlikely to have a long-lasting impact because of the child’s constantly changing capacities and experiences, which can override the impact of fetal stimulation (Lecanuet, Granier-Deferre, & DeCasper, 2005). In addition, although ordinary stimulation contributes to sensory functioning, excessive input can be hazardous. For example, nonhuman animal studies indicate that a sensitive period (see page 23 in Chapter 1) exists in which the fetal ear is highly susceptible to injury (Pierson, 1996). During that time, prolonged exposure to sounds that are harmless to the mature ear can permanently damage fetal inner-ear structures.

Period of the fetus: thirty-sixth week. This fetus fills the uterus. To nourish it, the umbilical cord and placenta have grown large. Vernix, a cheeselike substance, protects the skin from chapping. The fetus has accumulated fat to aid temperature regulation after birth. In two more weeks, it will be full term.


In the final three months, the fetus gains more than 5 pounds and grows 7 inches. During the eighth month, lanugo typically is shed. A layer of fat is added to assist with temperature regulation. The fetus also receives antibodies from the mother’s blood that protect against illnesses, since the newborn’s immune system will not work well until several months after birth. In the last weeks, most fetuses assume an upside-down position, partly because of the shape of the uterus and partly because the head is heavier than the feet. Growth slows, and birth is about to take place.


3.3a Cite factors that influence the impact of teratogens, and discuss evidence on the impact of known or suspected teratogens.

3.3b Describe the impact of additional maternal factors on prenatal development.

Although the prenatal environment is far more constant than the world outside the womb, many factors can affect the embryo and fetus. Yolanda and Jay learned that parents—and society as a whole—can do a great deal to create a safe environment for development before birth.

3.3.1 Teratogens

The term teratogen (from the Greek word teras, meaning “malformation”) refers to any environmental agent that causes damage during the prenatal period. The harm done by teratogens is not always simple and straightforward. It depends on the following factors:

Dose. As we discuss particular teratogens, you will see that larger doses over longer time periods usually have more negative effects.

Heredity. The genetic makeup of the mother and the developing organism plays an important role. Some individuals are better able than others to withstand harmful environments.

Other negative influences. The presence of several negative factors at once, such as additional teratogens, poor nutrition, and lack of medical care, can worsen the impact of a harmful agent.

Age. The effects of teratogens vary with the age of the organism at time of exposure. To understand this last idea, think back, once again, to the sensitive period concept introduced in Chapter 1. A sensitive period is a limited time span in which a part of the body or a behavior is biologically prepared to develop rapidly. During that time, it is especially sensitive to its surroundings. If the environment is harmful, then damage occurs, and recovery is difficult and sometimes impossible.

Figure 3.4 on page 98 summarizes prenatal sensitive periods. Look at it carefully, and you will see that some parts of the body, such as the brain and eye, have long sensitive periods that extend throughout prenatal development. For other parts, including the limbs and palate, sensitive periods are much shorter. Figure 3.4 also indicates that we can make some general statements about the timing of harmful influences. In the germinal period, before implantation, teratogens rarely have any impact. If they do, the tiny mass of cells is usually so damaged that it dies. Serious defects are most likely to arise during the embryonic period, when the foundations of all body parts emerge. During the fetal period, teratogenic damage is usually minor. However, organs such as the brain, ears, eyes, teeth, and genitals can still be strongly affected.

The effects of teratogens go beyond immediate physical damage. Some health effects may show up years later. Growing evidence indicates that certain teratogens exert long-term effects epigenetically, by modifying gene expression (see page 82 in Chapter 2) (Markunas et al., 2014). Furthermore, delayed psychological consequences can occur indirectly, as a result of physical damage. For example, a defect resulting from drugs the mother took during pregnancy can affect others’ reactions to the child as well as the child’s ability to explore the environment. Over time, parent–child interaction, peer relations, and cognitive, emotional, and social development may suffer.

Figure 3.4 Sensitive periods in prenatal development. Each organ or structure has a sensitive period, during which its development may be disturbed. Blue horizontal bars indicate highly sensitive periods. Green horizontal bars indicate periods that are somewhat less sensitive to teratogens, although damage can occur. (From Before We Are Born, 9th ed., by K. L. Moore, T. V. N. Persaud, & M. G. Torchia, p. 313. Copyright © 2016, adapted with permission from Elsevier, Inc.)

Notice how an important idea about development discussed in earlier chapters is at work here: bidirectional influences between child and environment. Now let’s look at what researchers have discovered about a variety of teratogens.

Prescription and Nonprescription

Drugs In the early 1960s, the world learned a tragic lesson about drugs and prenatal development. At that time, a sedative called thalidomide was widely available in Canada, Europe, and South America. When taken by mothers 4 to 6 weeks after conception, thalidomide produced gross deformities of the embryo’s developing arms and legs and, less frequently, damage to the ears, heart, kidneys, and genitals. About 7,000 infants worldwide were affected. Recent evidence suggests that thalidomide may exert its damaging effects through epigenetic mechanisms, including gene methylation (Ross & Desai, 2017). Furthermore, as children exposed to thalidomide grew older, many scored below average in intelligence. Perhaps the drug damaged the central nervous system directly. Or the child-rearing conditions of these youngsters with severe physical deformities may have impaired their intellectual development.

Another medication, a synthetic hormone called diethylstilbestrol (DES), was widely prescribed between 1945 and 1970 to prevent miscarriages. As daughters of these mothers reached adolescence and young adulthood, they showed unusually high rates of cancer of the vagina, malformations of the uterus, and infertility. When they tried to have children, their pregnancies more often resulted in prematurity, low birth weight, and miscarriage than those of non-DES-exposed women. Young men showed an increased risk of genital abnormalities and cancer of the testes (Goodman, Schorge, & Greene, 2011; Reed & Fenton, 2013).

Currently, the most widely used, potent teratogenic medication is a vitamin A derivative called isotretinoin, prescribed to treat severe acne and taken by hundreds of thousands of women of childbearing age in industrialized nations. Exposure during the first trimester results in eye, ear, skull, brain, heart, and immune system abnormalities (Yook et al., 2012). U.S. regulations for prescribing isotretinoin require female users to commit to avoiding pregnancy by using two methods of birth control.

Any drug with a molecule small enough to penetrate the placental barrier can enter the embryonic or fetal bloodstream. Yet many pregnant women continue to take over-the-counter medications without consulting their doctors. Some research suggests that aspirin use is linked to brain damage leading to impaired motor control, inattention, and overactivity, though other evidence fails to confirm these findings (Barr et al., 1990; Kozer et al., 2003; Thompson et al., 2014; Tyler et al., 2012). Coffee, tea, cola, and cocoa contain another frequently consumed drug, caffeine. High doses increase the risk of low birth weight (Sengpiel et al., 2013). Persistent intake of antidepressant medication is associated with an elevated incidence of premature delivery, low birth weight, respiratory distress at birth, and delayed motor development in infancy, but contrary evidence exists (Grigoriadis et al., 2013; Huang et al., 2014; Robinson, 2015).

A pregnant woman consults a nurse about her medications and their potential effects on embryonic and fetal development. Before taking any drug—prescription or nonprescription—expectant mothers must seriously consider its risks.


Because children’s lives are involved, we must take findings like these seriously. At the same time, we cannot be sure that these drugs actually cause the problems just mentioned. Often mothers take more than one drug. If the embryo or fetus is injured, it is hard to tell which drug might be responsible or whether other factors correlated with drug taking are at fault. Until we have more information, the safest course of action is the one Yolanda took: Avoid drugs as far as possible.

Unfortunately, many women do not know that they are pregnant during the early weeks of the embryonic period, when exposure to medications (and other teratogens) can be of greatest threat. In some instances, such as antidepressant use by severely depressed mothers, the benefits of drug treatment may outweigh its risks.

Illegal Drugs

The use of highly addictive mood-altering drugs, such as cocaine and heroin, has become more widespread, especially in poverty-stricken areas where these drugs provide a temporary escape from a daily life of hopelessness. Nearly 6 percent of U.S. pregnant women take these substances (Substance Abuse and Mental Health Services Administration, 2016).

Babies born to users of cocaine, heroin, or methadone (a less addictive drug used to wean people away from heroin) are at risk for a wide variety of problems, including prematurity, low birth weight, brain abnormalities, physical defects, breathing difficulties, and death around the time of birth (Behnke & Smith, 2013). In addition, these infants are born drug-addicted. They are often feverish and irritable and have trouble sleeping, and their cries are abnormally shrill—a common symptom among stressed newborns (Anand & Campbell-Yeo, 2015; Barthell & Mrozek, 2013). When mothers with many problems of their own must care for these babies, who are difficult to calm down, cuddle, and feed, behavior problems are likely to persist.

Throughout the first year, heroin- and methadone-exposed infants are less attentive to the environment than nonexposed babies, and their motor development is slow. After infancy, some children get better, while others remain jittery and inattentive (Hans & Jeremy, 2001). The kind of parenting they receive may explain why problems persist for some but not for others.

Evidence on cocaine suggests that some prenatally exposed babies develop lasting difficulties. Cocaine constricts the blood vessels, causing oxygen delivered to the developing organism to fall for 15 minutes following a high dose. It also can lead to deficits in production of neurons and their synaptic connections, as well as alter the chemical balance in the fetus’s brain. These effects may contribute to an array of cocaine-associated physical malformations, especially of the central nervous system and heart; brain hemorrhages and seizures; and delayed physical growth (Cain, Bornick, & Whiteman, 2013; Grewen et al., 2014; Li et al., 2013). An array of studies report perceptual, motor, attention, memory, language, reasoning, and externalizing behavior problems that persist into adolescence (Coyle, 2013; Richardson et al., 2015; Singer et al., 2015).

Other investigations, however, reveal no major negative effects of prenatal cocaine exposure (Ackerman, Riggins, & Black, 2010; Allen et al., 2014; Buckingham-Howes et al., 2013). These contradictory findings illustrate how difficult it is to isolate the precise damage caused by illegal drugs. Cocaine users vary greatly in the amount, potency, and purity of the cocaine they ingest. Also, they often take several drugs, display other high-risk behaviors, suffer from poverty and other stressors, and engage in insensitive caregiving—factors that worsen outcomes for children (Molnar et al., 2014). Researchers have yet to determine exactly what accounts for findings of cocaine-related damage in some studies but not in others.

Another drug, marijuana, has been legalized for medical and recreational use in some U.S. states. Studies have linked prenatal marijuana exposure to increased risk of low birth weight and newborn death and to attention, memory, and academic achievement difficulties; impulsivity and overactivity; and depression as well as anger and aggression in childhood and adolescence (Behnke & Smith, 2013; Goldschmidt et al., 2004; Gray et al., 2005; Hayatabakhsh et al., 2012; Jutras-Aswad et al., 2009). But as with heroin and cocaine, these consequences are not well-established.

However, a growing number of researchers believe that prenatal marijuana exposure delivers an initial, silent “hit” to the fetal brain, inducing epigenetic changes that heighten sensitivity to postnatal environmental stressors. Inadequate parenting, nutritional deprivation, or other stressful conditions may then deliver a second, powerful “hit” that impairs central nervous system functioning profoundly, resulting in long-lasting cognitive and emotional deficits (Calvigioni et al., 2014; Maccarrone et al., 2014; Richardson, Hestor, & McLemore, 2016). Both animal and human longitudinal studies offer support for this hypothesis, though more evidence is needed to confirm it.

Overall, the effects of illegal drugs are less consistent than the impact of two legal substances to which we now turn: tobacco and alcohol.


Although smoking has declined in Western nations, about 7 percent of U.S. women smoke during their pregnancies (Centers for Disease Control and Prevention, 2018b). The best-known effect of smoking during the prenatal period is low birth weight. But the likelihood of other serious consequences, such as miscarriage, prematurity, cleft lip and palate, blood vessel abnormalities, impaired heart rate and breathing during sleep, infant death, and asthma and cancer later in childhood, also increases (Geerts et al., 2012; Havstad et al., 2012; Howell, Coles, & Kable, 2008; Mossey et al., 2009). The more cigarettes a mother smokes, the greater the chances that her baby will be affected. If a pregnant woman stops smoking at any time, even during the third trimester, she reduces the likelihood that her infant will be born underweight and suffer from future problems (Polakowski, Akinbami, & Mendola, 2009). The earlier she stops, the more beneficial the effects.

Even when a baby of a smoking mother appears to be born in good physical condition, slight behavioral abnormalities may threaten the child’s development. Newborns of smoking mothers are less attentive to sights and sounds, display more muscle tension, are more emotionally reactive to frustration, and more often have colic (persistent crying). These findings suggest subtle negative effects on brain development (Espy et al., 2011; Shisler et al., 2017 Wiebe et al., 2014). Consistent with this view, prenatally exposed children and adolescents tend to have shorter attention spans, difficulties with impulsivity and overactivity, poorer memories, lower intelligence and achievement test scores, and higher levels of disruptive, aggressive behavior (Espy et al., 2011; Thakur et al., 2013).

Exactly how can smoking harm the fetus? Nicotine, the addictive substance in tobacco, constricts blood vessels, lessens blood flow to the uterus, and causes the placenta to grow abnormally. This reduces the transfer of nutrients, so the fetus gains weight poorly. Also, nicotine raises the concentration of carbon monoxide in the bloodstreams of both mother and fetus. Carbon monoxide displaces oxygen from red blood cells, damaging the central nervous system and slowing fetal body growth (Behnke & Smith, 2013). Other toxic chemicals in tobacco, such as cyanide and cadmium, contribute to its damaging effects. Research also suggests that prenatal exposure to cigarette smoke is a powerful epigenetic modifier of DNA, inducing widespread gene methylation that persists into adulthood (Lee et al., 2015; Tehranifar et al., 2018). These epigenetic changes may contribute to sustained impulsivity, overactivity, and oppositional behavior in childhood, adolescence, and beyond.

Maternal smoking during the prenatal period is associated with many serious consequences, including low birth weight and prematurity. This infant, born many weeks before his due date, breathes with the aid of a respirator.

© AURORA PHOTOS/Alamy Stock Photo

From one-third to one-half of nonsmoking pregnant women are “passive smokers” because their partners, relatives, or co-workers use cigarettes. Passive smoking is also related to low birth weight, infant death, childhood respiratory illnesses, and possible long-term attention, learning, and behavior problems (Best, 2009; Hawsawi, Bryant, & Goodfellow, 2015). Clearly, expectant mothers should avoid smoke-filled environments.


In his moving book The Broken Cord, Michael Dorris (1989), a Dartmouth College anthropology professor, described what it was like to rear his adopted son Adam, a Sioux Indian, who was born with fetal alcohol spectrum disorder (FASD), a term that encompasses a range of physical, mental, and behavioral outcomes caused by prenatal alcohol exposure. Children with FASD are generally given one of the following four diagnoses, which vary in severity: fetal alcohol syndrome (FAS), partial fetal alcohol syndrome (p-FAS), alcohol-related neurodevelopmental disorder (ARND), and alcohol-related birth defects (ARBD) (see Table 3.3) (Hoyme et al., 2016).

Table 3.3 Diagnostic Criteria for Fetal Alcohol Spectrum Disorder (FASD)



Fetal alcohol syndrome (FAS)

• At least two of three characteristic facial abnormalities

 – Short eyelid openings (measured horizontally)

 – Thin upper lip

 – Smooth or flattened philtrum (indentation between the nose and upper lip)

• Deficient physical growth (height or weight at or below the tenth percentile for child’s age)

• Deficient brain growth or profound brain injury, indicated either by a small head (at or below the tenth percentile) or confirmed through brain imaging

• Substantial cognitive impairment and behavioral impairment in self -regulation

Partial fetal alcohol syndrome (p-FAS)

• At least two of the three characteristic facial abnormalities

• Either deficient physical growth or profound brain injury

• Either substantial cognitive impairment or behavioral impairment in self-regulation

Alcohol-related neurodevelopmental disorder (ARND)

• Deficient brain growth or profound brain injury

• Either substantial cognitive impairment or behavioral impairment in self-regulation

• Typical physical growth and absence of facial abnormalities

Alcohol-related birth defects (ARBD)

• At least two of the three characteristic facial abnormalities

• Other alcohol-related physical malformations—for example, of the eyes, ears, heart, urinary tract, or hands

• Typical physical growth, absence of brain abnormalities, and absence of cognitive and behavioral deficits

Source: Hoyme et al., 2016.

Adam was diagnosed as having FAS. As is typical of this disorder, his mother drank heavily during pregnancy. Frequent binge drinking (consuming four or more drinks on a single occasion), especially early in pregnancy, elevates risk for FAS and p-FAS (Popova et al., 2018). For ARND, and ARBD, prenatal alcohol exposure, though confirmed, is usually less pervasive than for FAS and p-FAS (Mattson, Crocker, & Nguyen, 2012).

The brain abnormalities associated with FASD show up in diverse symptoms—for example, poor memory, language and communication, impulse control, attention span, activity level (overactivity), planning and reasoning, motor coordination, and academic and social skills. Additional physical defects—of the eyes, ears, nose, throat, heart, genitals, skeleton, hands, urinary tract, or immune system—may also be present.

Even when provided with enriched diets, babies with FAS or p-FAS fail to catch up in physical size during infancy or childhood. Cognitive and behavioral impairments are also permanent: In his teens and twenties, Adam had trouble concentrating and keeping a routine job, and he suffered from poor judgment. For example, he would buy something and not wait for change or would wander off in the middle of a task. He died at age 23, after being hit by a car. Adolescents and young adults with FAS, p-FAS, or ARND generally display persisting attention, impulse-control, and motor-coordination deficits, school failure, inappropriate social and sexual behaviors, trouble with the law, and mental health problems, including inability to manage stress, depression, and alcohol and drug abuse (Bertrand & Dang, 2012; Hellemans et al., 2010; Roszel, 2015). Still, as the Biology and Environment box on the following page illustrates, some recovery is possible for children with p-FAS and ARND through carefully designed intervention.

This child, whose mother drank heavily during pregnancy, has all three of the facial abnormalities characteristic of fetal alcohol syndrome (FAS): short eyelid openings, which make her eyes look widely spaced; a thin upper lip; and a flattened philtrum (the indentation between her nose and upper lip).

© Rick’s Photography/SHUTTERSTOCK

How does alcohol produce its devastating effects? First, it interferes with production and migration of neurons in the primitive neural tube. Neuroimaging findings confirm damage to many brain structures and abnormalities in brain functioning, including electrical and chemical activity involved in transferring messages from one part of the brain to another (de la Monte & Kril, 2014; Memo et al., 2013). Second, the body uses large quantities of oxygen to metabolize alcohol. A pregnant woman’s heavy drinking draws away oxygen that the developing organism needs for cell growth. Third, both animal and human research reveals widespread epigenetic changes in response to alcohol consumption, including altered methylation of many genes, that contribute to physical and brain abnormalities (Laufer et al., 2017; Lussier et al., 2018; Mandal et al., 2017). Other evidence suggests that paternal alcohol use around the time of conception can also alter gene expression, thereby playing a role in these damaging outcomes (Basavarajappa & Subbanna, 2016).

About 10 percent of U.S. pregnant women report drinking during the previous month, one-third of whom admit to binge drinking. An estimated 3 percent of U.S. infants are affected, with diagnoses of p-FAS, ARND, and ARBD occurring 3 to 4 times more often than full-blown FAS (Centers for Disease Control and Prevention, 2015; Roozen et al., 2016). Globally, an estimated 630,000 infants with FASD are born each year. The incidence is especially high in Eastern Europe, and South Africa has the highest rate in the world, at 11 percent (Lange et al., 2017).

As with heroin and cocaine, alcohol abuse is higher in poverty-stricken women. It is especially high among Native Americans, for whom the risk of a baby born with FAS is 20 to 25 times greater than for the rest of the U.S. population (Rentner, Dixon, & Lengel, 2012). Unfortunately, when affected girls later become pregnant, the poor judgment caused by the syndrome often prevents them from understanding why they themselves should avoid alcohol. Thus, the tragic cycle is likely to be repeated in the next generation.

How much alcohol is safe during pregnancy? Even mild drinking, less than one drink per day, can lead to slow physical growth, brain damage, and cognitive and behavioral impairments (Flak et al., 2014; Martinez-Frias et al., 2004). Recall that other factors—both genetic and environmental—can make some fetuses more vulnerable to teratogens. Therefore, no amount of alcohol is safe. Couples planning a pregnancy and expectant mothers should avoid alcohol entirely.

Biology and EnvironmentSelf-Regulation Therapy for Children with Fetal Alcohol Spectrum Disorder (FASD)

Self-regulation difficulties are so pervasive among children with the brain abnormalities caused by prenatal alcohol exposure that they are now regarded as a core deficit of FASD. A weakened capacity to manage one’s thoughts, emotions, and actions is apparent in high emotional reactivity, distractibility, and overactivity as early as infancy and in poor planning, reasoning, and social awareness in childhood. These behaviors are strong predictors of the high levels of mental health problems and lawbreaking associated with FASD by adolescence.

Until recently, treatments for FASD have shown either minimal or inconsistent effects (Murawski et al., 2015). But a new approach that targets a central deficit of diagnosed children—impaired self-regulation skills—shows considerable promise.

In several experiments, researchers randomly assigned 8- to 12-year-olds with p-FAS or ARND to either a therapy or a no-treatment control condition. In each investigation, therapy was based on a widely applied self-regulation intervention for school-age children called the Alert Program (Williams & Shellenberger, 1996). In 12 weekly sessions, Alert shows children how to monitor their thoughts, feelings, and behavior, noticing when their arousal level interferes with their ability to engage in everyday learning and social activities.

Using the analogy of a car engine running at different speeds, the Alert therapist helps children recognize when their engines are running “too quickly” (wired) or “too slowly” (sluggish). Then the therapist teaches strategies for adjusting the engine to run “just right” (focused on the task at hand). These include steps for planning ahead, identifying emotions in themselves and others, expressing feelings appropriately, and solving social problems, such as how to cooperate in a game with a peer. Finally, the therapist provides children with practice in selecting strategies independently and applying those strategies appropriately outside the therapeutic situation.

Relative to controls, children experiencing Alert improved considerably in regulation of behavior, especially in ability to inhibit irrelevant actions and control their emotions (Nash et al., 2015). In addition, parents of Alert children rated them as better regulated and as having fewer behavior problems—an outcome still evident at a six-month follow-up.

Furthermore, magnetic resonance imaging (MRI) brain scans gathered before and after the intervention revealed that Alert led to denser gray matter (darker tissue consisting mainly of neurons and their connective fibers) in regions of the cerebral cortex crucial for self-regulation, indicating that new synapses had formed (Soh et al., 2015). Treatment children also displayed more efficient functioning in these cerebral regions, which correlated with their ability to inhibit impulsive responding while playing a computer game (Nash et al., 2018). These findings suggest that it is possible to modify some of the brain damage caused by fetal alcohol exposure.

The researchers noted that the gains of treatment children were greatest on simple rather than complex self-regulation tasks—findings not surprising, given the significant brain pathology associated with p-FAS and ARND. At the same time, the shift in parents’ views of their children following Alert is impressive: It may spark favorable changes in the parent–child relationship that lead to continued progress, especially as therapists equip parents with knowledge of Alert therapeutic techniques.

The mother of a child with FASD helps her daughter with a homework assignment. School-age children with p-FAS and ARND who experienced Alert self-regulation therapy improved in ability to inhibit irrelevant actions and control their emotions, and their parents viewed them as having fewer behavior problems.



In Chapter 2, we saw that ionizing radiation can cause mutation, damaging DNA in ova and sperm. When mothers are exposed to radiation during pregnancy, the embryo or fetus can suffer additional harm. Defects due to ionizing radiation were tragically apparent in children born to pregnant women who survived the bombing of Hiroshima and Nagasaki during World War II. Similar abnormalities surfaced in the nine months following the 1986 Chernobyl, Ukraine, nuclear power plant accident. After each disaster, the incidence of miscarriage and babies born with brain damage, physical deformities, and slow physical growth rose dramatically. The risk of brain injury and intellectual disability is greatest from the end of the first trimester through the second trimester, when production and migration of neurons is especially high (Verreet et al., 2016; Yang, Ren, & Tang, 2017). Evacuation of residents in areas near the Japanese nuclear facility damaged by the March 2011 earthquake and tsunami was intended to prevent these devastating outcomes.

Even when a radiation-exposed baby seems unaffected, problems may appear later. For example, even low-level radiation, resulting from industrial leakage or medical radiation procedures, can increase the risk of childhood cancer (Fushiki, 2013). In middle childhood, prenatally exposed Chernobyl children had abnormal brain-wave activity, lower intelligence test scores, and rates of language and emotional disorders two to three times greater than those of nonexposed children in the surrounding area. Furthermore, the more tension parents reported, due to forced evacuation from their homes and worries about living in irradiated areas, the poorer their children’s emotional functioning (Loganovskaja & Loganovsky, 1999; Loganovsky et al., 2008). Stressful rearing conditions seemed to combine with the damaging effects of prenatal radiation to impair children’s development.

Women should do their best to avoid medical radiation during pregnancy. If dental, thyroid, chest, or other X-rays are necessary, insisting on the use of an abdominal shield is a key protective measure.

A pregnant woman is tested for exposure to radiation at an evacuation center following the Fukushima, Japan, nuclear power plant disaster in 2011. Radiation can cause devastating harm to the embryo or fetus and is particularly dangerous for the developing brain from the end of the first trimester through the second trimester.

© REUTERS/Kim Kyung-Hoon

Environmental Pollution

In industrialized nations, an astounding number of potentially dangerous chemicals are released into the environment, and many new pollutants are introduced each year. When 10 newborns were randomly selected from U.S. hospitals for analysis of umbilical cord blood, researchers uncovered a startling array of industrial contaminants—287 in all (Houlihan et al., 2005). They concluded that many babies are “born polluted” by chemicals that not only impair prenatal development but increase the chances of life-threatening diseases and health problems later on.

Certain pollutants cause severe prenatal damage. In the 1950s, an industrial plant released waste containing high levels of mercury into a bay providing seafood and water for the town of Minamata, Japan. Many children born at the time displayed physical deformities, intellectual disability, abnormal speech, difficulty in chewing and swallowing, and uncoordinated movements. High levels of prenatal mercury exposure disrupt production and migration of neurons, causing widespread brain damage (Caserta et al., 2013; Hubbs-Tait et al., 2005). Prenatal mercury exposure from maternal seafood diets predicts deficits in speed of cognitive processing, attention, and memory during the school years (Boucher et al., 2010, 2012; Lam et al., 2013). Pregnant women are wise to avoid eating long-lived predatory fish, such as swordfish, albacore tuna, and shark, which are heavily contaminated with mercury.

For many years, polychlorinated biphenyls (PCBs) were used to insulate electrical equipment, until research showed that, like mercury, they entered waterways and the food supply. In Taiwan, prenatal exposure to high levels of PCBs in rice oil resulted in low birth weight, discolored skin, deformities of the gums and nails, brain-wave abnormalities, and delayed cognitive development (Chen & Hsu, 1994; Chen et al., 1994). Steady, low-level PCB exposure is also harmful. Women who frequently ate PCB-contaminated fish, compared with those who ate little or no fish, had infants with lower birth weights, smaller heads, persisting attention and memory difficulties, and lower intelligence test scores in childhood (Boucher, Muckle, & Bastien, 2009; Polanska, Jurewicz, & Hanke, 2013; Stewart et al., 2008).

Another teratogen, lead, is present in paint flaking off the walls of old buildings and in certain materials used in industrial occupations. High levels of prenatal lead exposure are related to prematurity, low birth weight, brain damage, and a wide variety of physical defects. Even at low levels, affected infants and children show slightly poorer mental and motor development (Caserta et al., 2013; Jedrychowski et al., 2009).

Prenatal exposure to dioxins—toxic compounds resulting from incineration and burning of fuels, such as coal or oil—is linked to thyroid abnormalities in infancy and to an increased incidence of breast and uterine cancers in women, perhaps through altering hormone levels (ten Tusscher & Koppe, 2004). Even tiny amounts of dioxin in the paternal bloodstream cause a dramatic change in the sex ratio of offspring: Affected men father nearly twice as many girls as boys (Ishihara et al., 2007). Dioxin seems to impair the fertility of Y-bearing sperm prior to conception.

Finally, persistent air pollution inflicts substantial prenatal harm. Exposure to traffic-related fumes and smog is associated with reduced infant head size, low birth weight, elevated infant death rates, impaired lung and immune-system functioning, and later respiratory illnesses (Proietti et al, 2013; Ritz et al., 2014). In several large-scale studies, prenatal exposure to air pollution was linked to several childhood cancers, including leukemia and tumors of the eye and brain (Ghosh et al., 2013; Lavigne et al., 2017).

Infectious Disease

Most infectious illnesses women experience during pregnancy, such as the common cold, seem to have no impact on the embryo or fetus. However, as Table 3.4 illustrates, a few can cause extensive damage.


In the mid-1960s, a worldwide epidemic of rubella (three-day, or German, measles) led to the birth of more than 20,000 U.S. babies with serious defects and to 13,000 fetal and newborn deaths. Consistent with the sensitive period concept, the greatest damage occurs when rubella strikes during the embryonic period. More than 50 percent of infants whose mothers become ill during that time are born with some or all of the following: deafness; eye deformities, including cataracts; heart, genital, urinary, intestinal, bone, and dental defects; and intellectual disability. Infection during the fetal period is less harmful, but low birth weight, hearing loss, and bone defects may still occur. The organ damage inflicted by prenatal rubella often leads to lifelong health problems, including severe mental illness, diabetes, cardiovascular disease, and thyroid and immune-system dysfunction in adulthood (Duszak, 2009; Waldorf & McAdams, 2013). Routine vaccination in infancy and childhood has made new rubella outbreaks unlikely in industrialized nations. But over 100,000 cases of prenatal infection continue to occur each year, primarily in developing countries in Africa and Asia with weak or absent immunization programs (World Health Organization, 2017b).

Table 3.4 Effects of Some Infectious Diseases During Pregnancy



Physical Malformations

Intellectual Disability

Low Birth Weight and Prematurity


Acquired immune deficiency syndrome (AIDS)




Herpes simplex 2 (genital herpes)


Rubella (German measles)












✓ = established finding, ✗ = no present evidence, ? = possible effect that is not clearly established

Sources: Beckham et al., 2016; Kliegman et al., 2015; Waldorf & McAdams, 2013.

The human immunodeficiency virus (HIV), which can lead to acquired immune deficiency syndrome (AIDS), a disease that destroys the immune system, has infected increasing numbers of women over the past three decades. In developing countries, where 95 percent of new infections occur, more than half affect women. In South Africa, for example, 30 percent of all pregnant women are HIV-positive (Burton, Giddy, & Stinson, 2015). Untreated HIV-infected expectant mothers pass the deadly virus to the developing organism 10 to 20 percent of the time.

AIDS progresses rapidly in infants. By 6 months, weight loss, diarrhea, and repeated respiratory illnesses are common. The virus also causes brain damage, as indicated by seizures, gradual loss in brain weight, and delayed cognitive and motor development. Most untreated prenatal AIDS babies die by age 3 (Siberry, 2015). Antiretroviral drug therapy reduces prenatal transmission to less than 1 to 2 percent, and several babies born with HIV for whom aggressive retroviral treatment began within 2 days after birth appeared free of the disease (McNeil, 2014). However, antiretroviral drugs remain unavailable to at least one-third of HIV-infected pregnant women in developing countries (World Health Organization, 2017a).

As Table 3.4 reveals, the developing organism is especially sensitive to the family of herpes viruses, for which no vaccine exists. Among these, cytomegalovirus (the most frequent prenatal infection, transmitted through respiratory or sexual contact) and herpes simplex 2 (transmitted sexually) are especially dangerous. In both, the virus invades the mother’s genital tract, infecting babies either during pregnancy or at birth. Both diseases often have no symptoms, very mild symptoms, or symptoms with which people are unfamiliar, thereby increasing the likelihood of contagion. Pregnant women who are not in a mutually monogamous relationship are at greatest risk.

A Brazilian child lovingly cradles his 1-year-old brother who was born with microcephaly, a condition characterized by a severely damaged brain and unusually small head. The baby’s mother contracted the Zika virus during pregnancy.


A 2015 outbreak in Brazil of the Zika virus (mainly transmitted by mosquito but also through sexual contact with an infected person) drew widespread attention because of an associated rise in the number of babies born with microcephaly (unusually severe brain injury, evident in extremely small head size, as low as the first percentile) and eye deformities (Beckham et al., 2016; Brasil et al., 2016). As the disease spread through Central America, South America, and the Caribbean, Zika was declared a public health emergency. Expectant mothers are advised not to travel to countries or regions with Zika outbreaks. At present, no vaccine is available.

Bacterial and Parasitic Diseases

Table 3.4 also includes several bacterial and parasitic diseases. Among the most common is toxoplasmosis, caused by a parasite found in many animals. Pregnant women may become infected from handling contaminated soil while gardening, having contact with the feces of infected cats, or eating raw or undercooked meat or unwashed fruits and vegetables. About 40 percent of women who have the disease transmit it to the developing organism. If it strikes during the first trimester, it is likely to cause eye and brain damage. Later infection is linked to mild visual and cognitive impairments (Wallon et al., 2013). Expectant mothers can avoid toxoplasmosis by having pet cats checked for the disease, and turning over the care of litter boxes and the garden to other family members, and making sure that the meat they eat is well-cooked.

3.3.2 Other Maternal Factors

Besides avoiding teratogens, expectant parents can support prenatal development in other ways. In the following sections, we examine the influence of maternal exercise, nutrition, emotional well-being, blood type, and age.


In healthy, physically fit women, regular moderate exercise, such as walking, swimming, biking, or an aerobic workout, is related to improved fetal cardiovascular functioning, higher birth weight, and a reduction in risk of certain complications, such as pregnancy-induced maternal diabetes, high blood pressure, and premature birth (Artal, 2015; Jukic et al., 2012). However, frequent, vigorous exercise, especially late in pregnancy, results in lower birth weight than in healthy, nonexercising controls (Clapp et al., 2002; Leet & Flick, 2003). Hospital-sponsored childbirth education programs frequently offer exercise classes and suggest appropriate routines that help prepare for labor and delivery.

During the last trimester, when the abdomen grows very large, mothers have difficulty moving freely and often must cut back on exercise. Most women, however, do not engage in sufficient moderate exercise during pregnancy to promote their own and their baby’s health. An expectant mother who remains fit experiences fewer physical discomforts in the final weeks.

Pregnant women with health problems, such as circulatory difficulties or a history of miscarriages, should consult their doctor about a physical fitness routine. For these mothers, exercise (especially the wrong kind) can endanger the pregnancy.


During the prenatal period, when children are growing more rapidly than at any other time, they depend totally on the mother for nutrients. A healthy diet, consisting of a gradual increase in calories that results in a weight gain of 25 to 30 pounds (10 to 13.5 kilograms) helps ensure the health of mother and baby.

Prenatal malnutrition can cause serious damage to the central nervous system. The poorer the mother’s diet, the greater the loss in brain weight, especially if malnutrition occurs during the third trimester, when the brain is increasing rapidly in size. An inadequate diet during pregnancy can also distort the structure of the liver, kidney, pancreas, and other organs, predisposing the child to later health problems. As Figure 3.5 illustrates, large-scale studies reveal a consistent link between low birth weight and high blood pressure, cardiovascular disease, and diabetes in adulthood, even after many other prenatal and postnatal health risks were controlled (Johnson & Schoeni, 2011).

Because poor nutrition suppresses development of the immune system, prenatally malnourished babies frequently catch respiratory illnesses. In addition, they are often irritable and unresponsive to stimulation. Like drug-addicted newborns, they have a high-pitched cry that is particularly distressing to their caregivers. In poverty-stricken families, these effects quickly combine with a stressful home life. Delays in motor, attention, and memory development, low intelligence test scores, and serious learning problems become more apparent with age (Monk, Georgieff, & Osterholm, 2013).

Many studies show that providing pregnant women with an adequate quantity of food has a substantial impact on the health of their newborn babies. Vitamin–mineral enrichment is also crucial. For example, taking a folic acid supplement around the time of conception reduces by more than 70 percent abnormalities of the neural tube, such as anencephaly and spina bifida (see Table 2.2 on page 62). Folic acid supplementation early in pregnancy also lessens the risk of other physical defects, including cleft lip and palate, circulatory system and urinary tract abnormalities, and limb deformities. Furthermore, adequate folic acid intake during the last 10 weeks of pregnancy cuts in half premature delivery and low birth weight (Goh & Koren, 2008; Hovdenak & Haram, 2012).

Figure 3.5 Relationship of low birth weight to disease risk in adulthood. In a follow-up of more than 2,000 U.S. births at age 50, low birth weight was associated with a greatly increased incidence of high blood pressure, heart disease, stroke, and diabetes after many other prenatal and postnatal health risks were controlled. (Based on Johnson & Schoeni, 2011.)

Because of these findings, U.S. government guidelines recommend that all women of childbearing age consume 0.4 milligram of folic acid per day. For women who have previously had a pregnancy affected by a neural tube defect, the recommended amount is 4 milligrams (dosage must be carefully monitored, as excessive intake can be harmful) (Centers for Disease Control and Prevention, 2017d). Because many U.S. pregnancies are unplanned, government regulations mandate that bread, flour, rice, pasta, and other grain products be fortified with folic acid.

A government-supported farmers’ market nutrition program enables this low-income expectant mother to purchase fruits and vegetables. A maternal diet rich in vitamins and minerals can help protect prenatal brain development and prevent diverse birth defects.


Other vitamins and minerals also have established benefits. Enriching women’s diets with calcium helps prevent maternal high blood pressure and low birth weight. Adequate magnesium and zinc reduce the risk of many prenatal and birth complications (Hovdenak & Haram, 2012). Fortifying table salt with iodine virtually eradicates infantile hypothyroidism—a condition of stunted physical growth and brain injury caused by prenatal iodine deficiency that is a common cause of intellectual disability in many parts of the world (Williams, 2008). And sufficient vitamins C and E and iron beginning early in pregnancy promote placental growth, healthy birth weight, and brain development. Prenatal iron deficiency, in particular, is linked to deficiencies in neural connectivity and structural alterations in the brain. Affected children, adolescents, and young adults score lower on measures of self-regulation, memory, and motor skills (Kennedy et al., 2016; Klemmensen et al., 2009; Lukowski et al., 2010; Monk et al., 2016). Nevertheless, a supplement program should complement, not replace, efforts to improve maternal diets during pregnancy. For women who do not get enough food or an adequate variety of foods, multivitamin tablets are a necessary, but not sufficient, intervention.

Although prenatal malnutrition is highest in developing countries, it also occurs in the industrialized world. The U.S. Special Supplemental Food Program for Women, Infants, and Children (WIC), which provides food packages and nutrition education to low-income pregnant women, reaches about 90 percent of those who qualify because of their extremely low incomes (U.S. Department of Agriculture, 2018). But many U.S. women who need nutrition intervention are not eligible for WIC.

Emotional Stress

When women experience severe emotional stress during pregnancy, their babies are at risk for a wide variety of difficulties. Intense anxiety—especially during the first two trimesters—is associated with higher rates of miscarriage, prematurity, low birth weight, physical defects, infant respiratory and digestive illnesses, colic (persistent infant crying), sleep disturbances, and irritability during the child’s first three years (Dunkel-Shetter & Lobel, 2012; Glover, Ahmed-Salim, & Capron, 2016; Field, 2011). Prenatal stressors consistently found to impair later physical and psychological well-being include chronic strain due to poverty; partner abuse; major negative life events such as divorce or death of a family member; disasters such as earthquakes or terrorist attacks; and fears specific to pregnancy and childbirth, including persistent anxiety about the health and survival of the baby and oneself. It is important to note that mild to moderate occasional stress has no adverse impact.

How can severe maternal stress affect prenatal development? When we experience fear and anxiety, stress hormones released into our bloodstream—such as cortisol and epinephrine (adrenaline), known as the “flight or fight” hormones—cause us to be “poised for action.” Large amounts of blood are sent to parts of the body involved in the defensive response—the brain, the heart, and the muscles in the arms, legs, and trunk. Blood flow to other organs, including the uterus, may be reduced. As a result, the fetus is deprived of a full supply of oxygen and nutrients.

Maternal stress hormones also cross the placenta, causing a dramatic rise in fetal stress hormones (evident in the amniotic fluid) and, therefore, in fetal heart rate, blood pressure, blood glucose, and activity level (Kinsella & Monk, 2009; Weinstock, 2008). Excessive fetal stress is related to structural alterations in the infant brain that are linked to mood disorders in later life (O’Donnell & Meaney, 2016; Sandman, Glynn, & Davis, 2016). Infants and children of mothers who experienced severe prenatal anxiety display cortisol levels that are either abnormally high or abnormally low, both of which signal reduced physiological capacity to manage stress. Recall from Chapter 2 that prenatal epigenetic changes, through gene methylation, may be partly or largely responsible (Monk et al., 2016).

Maternal emotional stress during pregnancy is associated with diverse negative behavioral outcomes in childhood and adolescence, including anxiety, depression, short attention span, anger, aggression, overactivity, and lower intelligence test scores, above and beyond the impact of other risks, such as maternal smoking during pregnancy, low birth weight, postnatal maternal anxiety, and low SES (Coall et al., 2015; Monk, Georgieff, & Osterholm, 2013). Furthermore, similar to prenatal malnutrition, overwhelming the fetus with maternal stress hormones heightens susceptibility to later illness, including infectious diseases in childhood and cardiovascular disease and diabetes in adulthood (Nielsen et al., 2011; Reynolds, 2013).

However, stress-related prenatal complications are greatly reduced when mothers have partners, other family members, or friends who offer social support (Bloom et al., 2013; Luecken et al., 2013). The relationship of social support to positive pregnancy outcomes and subsequent child development is particularly strong for economically disadvantaged women, who often lead highly stressful lives (see the Social Issues: Health box on page 110).

Look and Listen

List prenatal environmental factors that can compromise later cognitive and social development. Ask several adults who hope someday to be parents to explain what they know about each factor. How great is their need for prenatal education?

RH Factor Incompatibility

When inherited blood types of mother and fetus differ, serious problems sometimes result. The most common cause of these difficulties is Rh factor incompatibility. When the mother is Rh-negative (lacks the Rh blood protein) and the father is Rh-positive (has the protein), the baby may inherit the father’s Rh-positive blood type. (Because Rh-positive blood is dominant and Rh-negative blood is recessive, the chances are good that a baby will be Rh-positive.) If even a little of a fetus’s Rh-positive blood crosses the placenta into the Rh-negative mother’s bloodstream, she begins to form antibodies to the foreign Rh protein. If these enter the fetus’s system, they destroy red blood cells, reducing the oxygen supply to organs and tissues. Intellectual disability, miscarriage, heart damage, and infant death can occur.

It takes time for the mother to produce Rh antibodies, so firstborn children are rarely affected. The risk increases with each additional pregnancy. Fortunately, Rh incompatibility can be prevented in most cases. After the birth of each Rh-positive baby, Rh-negative mothers are routinely given a vaccine to prevent the buildup of antibodies. In emergency cases, blood transfusions can be performed immediately after delivery or, if necessary, even before birth.

Maternal Age

First births to women in their thirties and early forties have increased dramatically over the past several decades (Martin et al., 2018b). Many people are delaying childbearing until their education is complete, their careers are established, and they know they can support a child. In Chapter 2, we noted that women who delay childbearing until their thirties or forties face increased risk of infertility, miscarriage, and babies with chromosomal defects. Are other pregnancy complications more common for older mothers? Research indicates that healthy women in their thirties have about the same rates as those in their twenties. Thereafter, as Figure 3.6 reveals, complication rates increase, with a sharp rise among 50- to 55-year-olds—an age at which, because of menopause (end of menstruation) and aging reproductive organs, few women can conceive naturally (Salihu et al., 2003; Usta & Nassar, 2008).

Figure 3.6 Relationship of maternal age to prenatal and birth complications. Complications increase after age 40, with a sharp rise between 50 and 55 years. See page 111 for a description of preeclampsia. (Adapted from Salihu et al., 2003.)

Social Issues: HealthThe Nurse–Family Partnership: Reducing Maternal Stress and Enhancing Child Development Through Social Support

At age 17, Denise—an unemployed high-school dropout living with her disapproving parents—gave birth to Tara. Having no one to turn to for help during pregnancy and beyond, Denise felt overwhelmed and anxious much of the time. Tara was premature and had breathing difficulties, cried uncontrollably, slept erratically, and suffered from frequent minor illnesses throughout her first year. When she reached school age, she had trouble keeping up academically, and her teachers described her as distractible, unable to sit still, angry, and uncooperative.

The Nurse–Family Partnership—currently implemented in hundreds of counties across 40 U.S. states, Washington, D.C., U.S. Virgin Islands, and many Tribal communities, and internationally in Australia, Canada, Bulgaria, Norway, England, Northern Ireland, and Scotland—is a voluntary home visiting program for first-time, economically disadvantaged expectant mothers like Denise. Its goals are to reduce pregnancy and birth complications, promote competent early caregiving, and improve family conditions, thereby protecting children from lasting adjustment difficulties.

A registered nurse visits the home weekly during the first month after enrollment, twice a month during the remainder of pregnancy and through the middle of the child’s second year, and then monthly until age 2. In these sessions, the nurse provides the mother with intensive social support—a sympathetic ear; assistance in accessing health and other community services and the help of family members (especially fathers and grandmothers); and encouragement to finish high school, find work, and engage in future family planning.

To evaluate the program’s effectiveness, researchers randomly assigned large samples of mothers at risk for high prenatal stress (due to teenage pregnancy, poverty, and other negative life conditions) to nurse-visiting or comparison conditions (just prenatal care, or prenatal care plus infant referral for developmental problems). Families were followed through their child’s school-age years and, in one experiment, into adolescence (Kitzman et al., 2010; Olds et al., 2004, 2007; Rubin et al., 2011).

As kindergartners, Nurse–Family Partnership children obtained higher language and intelligence test scores. And at both ages 6 and 9, the children of home-visited mothers in the poorest mental health during pregnancy exceeded comparison children in academic achievement and displayed fewer behavior problems. Furthermore, from their baby’s birth on, home-visited mothers were on a more favorable life course: They had fewer subsequent births, longer intervals between their first and second births, more frequent contact with the child’s father, more stable intimate partnerships, less welfare dependence, and a greater sense of control over their lives—key factors in reducing subsequent prenatal stress and in protecting children’s development. Perhaps for these reasons, adolescent children of home-visited mothers continued to be advantaged in academic achievement and reported less alcohol use and drug-taking than comparison-group agemates.

Other findings revealed that professional nurses, compared with trained paraprofessionals, were far more effective in preventing outcomes associated with prenatal stress, including high infant fearfulness to novel stimuli and delayed mental development (Olds et al., 2002). Nurses were probably more proficient in individualizing program guidelines to fit the strengths and challenges faced by each family. They also might have had unique legitimacy as experts in the eyes of stressed mothers, more easily convincing them to take steps to reduce pregnancy complications that can trigger persisting developmental problems—such as those Tara displayed.

The Nurse–Family Partnership is highly cost-effective (Miller, 2015). For every $1 spent, it saves more than five times as much in public spending on pregnancy complications, preterm births, and child and youth health, learning, and behavior problems.

The Nurse–Family Partnership provides this first-time mother with regular home visits from a registered nurse. In follow-up research, children of home-visited mothers developed more favorably—cognitively, emotionally, and socially—than comparison children.


In the case of teenage mothers, does physical immaturity cause prenatal complications? As we will see in Chapter 4, infants born to teenagers have a higher rate of problems, but not directly because of maternal age. Most pregnant teenagers come from low-income backgrounds, where stress, poor nutrition, and health problems are common.


3.4 Explain why early and regular health care is vital during the prenatal period.

Yolanda’s pregnancy, like most others, was free of complications. But unexpected difficulties can arise, especially if mothers have health problems. For example, an estimated 9 percent of expectant women are diagnosed with gestational diabetes, impaired glucose tolerance that emerges during pregnancy (DeSisto, Kim, & Sharma, 2014). All diabetic women need careful prenatal monitoring. Extra glucose in the mother’s bloodstream causes the fetus to grow larger than average, making pregnancy and birth problems more common. Furthermore, these infants are at increased risk of becoming overweight or obese and developing type 2 diabetes (Kampmann et al., 2015). Maternal high blood glucose also greatly elevates the chances of physical malformations and compromises prenatal brain development: It is linked to poorer attention, memory, and learning in infancy and early childhood (Hami et al., 2015).

Another complication, experienced by 5 to 10 percent of pregnant women, is preeclampsia (sometimes called toxemia), in which blood pressure increases sharply and the face, hands, and feet swell in the last half of pregnancy. Untreated preeclampsia can cause brain hemorrhages and kidney failure in expectant mothers, damage to the placenta, and fetal death. Usually, hospitalization, bed rest, and drugs can lower blood pressure to a safe level (Bokslag et al., 2016). If not, the baby must be delivered at once.

Unfortunately, 6 percent of pregnant women in the United States wait until after the first trimester to seek prenatal care or receive none at all. As Figure 3.7 shows, inadequate health care is far more common among low-income, ethnic minority mothers. Their infants are three times more likely to be born underweight and five times more likely to die than babies of mothers who receive early medical attention (Child Trends, 2015). Although government-sponsored health services for low-income pregnant women have expanded, some do not qualify and must pay for at least part of their care. As we will see when we address cross-national comparisons of health care policies in Chapter 4, in nations where affordable health care is universally available, late-care pregnancies and maternal and infant health problems are greatly reduced.

Figure 3.7 Expectant mothers in the United States with late (after the first trimester) or no prenatal care. From 7 to 11 percent of low-income ethnic minority mothers, and about 10 percent of adolescent mothers, receive inadequate prenatal care. (Based on Child Trends, 2015.)

Cultural InfluencesCulturally Sensitive Prenatal Health Care: Perspectives of Expectant Mothers

Compared with their European-American counterparts, low-income, ethnic minority expectant mothers are consistently less likely to access early and regular prenatal care—a difference linked to increased rates of low birth weight, prematurity, newborn death, and other negative birth outcomes (Cox et al., 2011; Kitsantas & Gaffney, 2010). When minority mothers do come in for prenatal appointments, they tend to report more negative experiences with health care providers (Wheatley et al., 2008). They perceive the care they receive to be poor quality, which discourages them from further seeking care, with profound implications for maternal and newborn health.

In several studies, researchers asked ethnic minority mothers who had recently given birth about their prenatal health care experiences. Many highlighted inadequacies in provider–patient communication while expressing a strong desire for culturally sensitive care. Noting that too often, doctors and nurses focused narrowly on completing required tests and conveying results, one mother concluded, “[W]e’re numbers and not people” (Coley et al., 2018, p. 161).

Though they readily acknowledged the need for medical procedures, minority mothers regarded the interpersonal side of prenatal visits as essential to quality care. An African-American mother illustrated what culturally sensitive care meant to her: “[for example] being aware of if you have a sickle-cell patient, … really doing your homework on the emotional side of what it means” (p. 161).

Hispanic mothers described provider–patient communication as especially challenging, due to language barriers and the fears of many that seeking prenatal care might threaten their immigrant status. In addition, they perceived doctors and nurses who rushed through appointments while appearing impatient and unfriendly as rude, angry, uncaring, and unreliable. In contrast, they judged those who took time to help reticent or confused patients to be caring and believable (Bergman & Connaughton, 2013). Spanish-speaking mothers consistently stressed the importance of having Spanish-speaking doctors, nurses, or interpreters available to overcome cultural differences, ensure patient understanding, and avoid medical errors.

Many new mothers noted that lack of cultural competence increased the chances that health care providers would harbor biased assumptions and behave disrespectfully. In a survey of several thousand new mothers, 20 percent of minority respondents reported poor treatment by doctors, nurses, or front desk staff due to race, ethnicity, or language (Attanasio & Kozhimannil, 2015). Discrimination in health care settings is associated with an array of negative outcomes, including unraveling of patient trust, reduced patient adherence to treatment recommendations, missed subsequent appointments, and declines in patient health (Hausmann et al., 2011; Weech-Maldonado et al., 2012).

Increasing the cultural sensitivity of prenatal care by strengthening provider–patient communication is vital for improving health outcomes for babies. In one strategy called group prenatal care, after each medical checkup, trained leaders provide low-income ethnic minority expectant mothers with a group discussion session—conducted in their native language—and encourage them to talk about important health issues (Carter et al., 2016; Catling et al., 2015). Compared to mothers receiving traditional brief appointments with little opportunity to ask questions, participants in group prenatal care are more satisfied with their health care experiences and engage in more health-promoting behaviors, and the incidence of prematurity and low birth weight is reduced.

Participants in a group prenatal care program meet after individual checkups to discuss important health issues in a culturally sensitive environment. Compared to mothers receiving traditional brief appointments, group care mothers experience a reduced incidence of prematurity and low birth weight.

Centering Healthcare Institute

Besides financial hardship, situational barriers (difficulty finding a doctor, getting an appointment, and arranging transportation) and personal barriers (psychological stress, the demands of taking care of other young children, family crises, and ambivalence about the pregnancy) can prevent mothers from seeking prenatal care (Mazul, Salm Ward, & Ngui, 2017). Many also engage in high-risk behaviors, such as smoking and drug abuse, which they do not want to reveal to health professionals.

Applying What We Know

Do’s and Don’ts for a Healthy Pregnancy



Do make sure that you have been vaccinated against infectious diseases that are dangerous to the embryo and fetus, such as rubella, before you get pregnant. Most vaccinations are not safe during pregnancy.

Do see a doctor as soon as you suspect that you are pregnant, and continue to get regular medical checkups throughout pregnancy.

Do eat a well-balanced diet and take vitamin–mineral supplements, as prescribed by your doctor, both prior to and during pregnancy. Gain 25 to 30 pounds gradually.

Do obtain literature from your doctor, library, or bookstore about prenatal development. Ask your doctor about anything that concerns you.

Do keep physically fit through moderate exercise. If possible, join a special exercise class for expectant mothers.

Do avoid emotional stress. If you are a single expectant mother, find a relative or friend on whom you can rely for emotional support.

Do get plenty of rest. An overtired mother is at risk for pregnancy complications.

Do enroll in a prenatal and childbirth education class with your partner or other companion. When parents know what to expect, the nine months before birth can be one of the most joyful times of life.

Don’t take any drugs without consulting your doctor.

Don’t smoke. If you have already smoked during part of your pregnancy, cut down or, better yet, quit. If other members of your family smoke, ask them to quit or to smoke outside.

Don’t drink alcohol from the time you decide to get pregnant.

Don’t engage in activities that might expose your embryo or fetus to environmental hazards, such as radiation or chemical pollutants. If you work in an occupation that involves these agents, ask for a safer assignment or a leave of absence.

Don’t engage in activities that might expose your embryo or fetus to harmful infectious diseases, such as toxoplasmosis.

Don’t choose pregnancy as a time to go on a diet.

Don’t gain too much weight during pregnancy. A very large weight gain is associated with complications.

For these women, assistance in making appointments, drop-in child-care centers, and free or low-cost transportation are vital. As the Cultural Influences box on page 112 reveals, culturally sensitive health-care practices, emphasizing open communication between health-care providers and pregnant women that is respectful of patients’ values and needs, are also helpful. Refer to Applying What We Know above, which lists “do’s and don’ts” for a healthy pregnancy, based on our discussion of the prenatal environment.

During a routine visit, a woman views an ultrasound image of her developing fetus. All pregnant women need regular prenatal care to protect their health and that of their babies.

© Hero Images Inc/Alamy Stock Photo

Ask Yourself

Connect ■ Using what you learned about research strategies in Chapter 1, explain why it is difficult to determine the prenatal effects of many environmental agents, such as drugs and pollution.

Apply ■ Nora, pregnant for the first time, believes that a few cigarettes and a glass of wine a day won’t be harmful. Provide Nora with research-based reasons for not smoking or drinking.

Reflect ■ If you had to choose five environmental influences to publicize in a campaign aimed at promoting healthy prenatal development, which ones would you choose, and why?


3.1 Motivations for Parenthood (p. 87)

3.1 Discuss factors that contribute to contemporary adults’ decision making about parenthood, including timing of childbearing and family size.

Compared to a few decades ago, today adults in Western industrialized nations are freer to choose whether, when, and how to have children. Among contextual factors that affect their decision making are financial circumstances, religious values, partnership changes, career goals, and government and workplace family policies.

Childbearing motivations have also changed over time, increasingly emphasizing individual fulfillment and deemphasizing obligation to society.

In the United States and other industrialized nations, the overall fertility rate has declined substantially over the past decade, a trend largely due to delayed marriage and parenthood, which results in adults having fewer children.

Contrary to widespread belief, smaller families do not make brighter children. The higher birth rate of low-SES women accounts for the association between large family size and lower intelligence test scores of all siblings.

Reproductive capacity declines with age, especially after 35, and risk of chromosomal and other genetically influenced disorders increases. Because highly educated women with demanding careers are especially likely to delay parenthood, they may not realize their childbearing goals.

3.2 Prenatal Development (p. 90)

3.2 List the three periods of prenatal development, and describe the major milestones of each.

The germinal period lasts about two weeks, from fertilization through implantation of the blastocyst in the uterine lining. Structures that support prenatal growth begin to form, including the amnion, chorion, placenta, and umbilical cord.

During the period of the embryo, weeks 2 through 8, the foundations for all body structures are laid down. The neural tube forms and the nervous system starts to develop. Other organs follow rapidly. By the end of this period, the embryo responds to touch and can move.

During the period of the fetus, the organism increases rapidly in size. By the middle of the second trimester, vernix and lanugo have emerged to protect the skin. At the end of the second trimester, most of the brain’s neurons are in place.

The fetus reaches the age of viability at the beginning of the third trimester, between 22 and 26 weeks. The brain continues to develop rapidly, and new sensory and behavioral capacities emerge, including taste and odor preferences, pain sensitivity, and the ability to distinguish the tone and rhythm of different voices and sounds. Gradually the lungs mature, the fetus fills the uterus, and birth nears.

3.3 Prenatal Environmental Influences (p. 97)

3.3a Cite factors that influence the impact of teratogens, and discuss evidence on the impact of known or suspected teratogens.

The impact of teratogens varies with amount and length of exposure, genetic makeup of mother and developing organism, age of the developing organism (serious defects are most likely to occur during embryonic period), and the presence of other negative factors. Growing evidence indicates that certain teratogens exert long-term effects epigenetically.

The most widely used potent teratogenic medication is isotretinoin, a treatment for severe acne. Evidence on other common medications, such as aspirin, caffeine, and antidepressants, is mixed, and their prenatal impact is hard to separate from other correlated factors.

Babies born to users of cocaine, heroin, or methadone are at risk for a wide variety of problems, including prematurity, low birth weight, brain abnormalities, physical defects, breathing difficulties, and infant death. Lasting negative effects, however, are not well-established.

By inducing epigenetic changes that heighten sensitivity to postnatal environmental stressors, prenatal marijuana exposure may lead to long-term cognitive and emotional deficits.

Infants whose parents use tobacco are often born underweight, may have physical defects, and are at risk for long-term health, attention, learning, and behavior problems.

Maternal alcohol consumption can lead to fetal alcohol spectrum disorder (FASD). Fetal alcohol syndrome (FAS) and partial fetal alcohol syndrome (p-FAS), resulting from heavy drinking during pregnancy, involve facial abnormalities, deficient physical growth, brain damage, and substantial cognitive and behavioral impairments. In less severe forms—alcohol-related neurodevelopmental disorder (ARND) and alcohol-related birth defects (ARBD)—alcohol exposure is usually less pervasive. Self-regulation therapy for school-age children with p-FAS and ARND leads to more efficient neural functioning and gains on simple self-regulation tasks.

Prenatal exposure to high levels of ionizing radiation, mercury, PCBs, lead, and dioxins leads to physical malformations and severe brain damage. Low-level exposure has been linked to cognitive deficits and emotional and behavioral disorders. Persistent air pollution is associated with low birth weight and impaired lung and immune-system functioning.

Among infectious diseases, rubella causes wide-ranging abnormalities. Babies with prenatally transmitted HIV rapidly develop AIDS, leading to brain damage and early death. Antiretroviral drug therapy dramatically reduces prenatal transmission. Cytomegalovirus, herpes simplex 2, and toxoplasmosis can also be devastating to the embryo and fetus. Prenatal exposure to the Zika virus is associated with microcephaly and eye deformities.

3.3b Describe the impact of additional maternal factors on prenatal development.

Exercise during pregnancy is linked to improved fetal cardiovascular functioning, higher birth weight, and reduced risk of pregnancy complications.

Prenatal malnutrition can lead to low birth weight, damage to the brain and other organs, and suppression of immune system development.

Folic acid supplements can greatly reduce the risk of physical defects, premature delivery, and low birth weight. Other vitamins and minerals also have established benefits.

Severe maternal emotional stress is linked to pregnancy complications and may impair children’s capacity to manage stress, thereby elevating their risk for diverse negative behavioral outcomes and physical illnesses. Providing mothers with social support greatly reduces these consequences.

Rh factor incompatibility can lead to oxygen deprivation, brain and heart damage, and infant death.

Older mothers face increased risk of miscarriage, babies with chromosomal defects, and, after age 40, a rise in other pregnancy complications. Poor health and environmental risks associated with low income explain higher rates of pregnancy complications in adolescent mothers.

3.4 The Importance of Prenatal Health Care (p. 111)

3.4 Explain why early and regular health care is vital during the prenatal period.

Unexpected complications, such as gestational diabetes and preeclampsia, can threaten any pregnancy. Inadequate prenatal health care is common among adolescent and low-income, ethnic minority mothers, whose babies are more likely to be born underweight and to die than infants of mothers with good prenatal care. Culturally sensitive health-care practices can help overcome the barriers that discourage low-income, ethnic minority mothers from seeking care.


age of viability (p. 95)

alcohol-related birth defects (ARBD) (p. 101)

alcohol-related neurodevelopmental disorder (ARND) (p. 101)

amnion (p. 91)

chorion (p. 93)

embryo (p. 93)

fetal alcohol spectrum disorder (FASD) (p. 101)

fetal alcohol syndrome (FAS) (p. 101)

fetus (p. 94)

germinal period (p. 91)

implantation (p. 91)

lanugo (p. 95)

neural tube (p. 94)

partial fetal alcohol syndrome (p-FAS) (p. 101)

placenta (p. 93)

Rh factor incompatibility (p. 109)

teratogen (p. 97)

trimesters (p. 94)

umbilical cord (p. 93)

vernix (p. 95)



Debjyoti Sakar, 12 years, India

Relatives approach a mother and her newborn to welcome the baby into the family. In Chapter 4, we explore the birth process, the marvelous competencies of the newborn, and the challenges of new parenthood.

Reprinted with permission from The International Museum of Children’s Art, Oslo, Norway


4.1 The Stages of Childbirth

Stage 1: Dilation and Effacement of the Cervix • Stage 2: Delivery of the Baby • Stage 3: Birth of the Placenta • The Baby’s Adaptation to Labor and Delivery • The Newborn Baby’s Appearance • Assessing the Newborn’s Physical Condition: The Apgar Scale

4.2 Approaches to Childbirth

Natural, or Prepared, Childbirth • Home Delivery

4.3 Medical Interventions

Fetal Monitoring • Labor and Delivery Medication • Instrument Delivery • Cesarean Delivery

4.4 Birth Complications

Oxygen Deprivation • Preterm and Low-Birth-Weight Infants • Birth Complications, Parenting, and Resilience

■Cultural Influences: A Cross-National Perspective on Health Care and Other Policies for Parents and Newborn Babies

4.5 The Newborn Baby’s Capacities

Reflexes • States • Sensory Capacities • Neonatal Behavioral Assessment

■Social Issues: Health: The Mysterious Tragedy of Sudden Infant Death Syndrome

4.6 The Transition to Parenthood

Early Parent–Infant Contact • Changes in the Family System • Single-Mother Families • Parent Interventions

■Biology and Environment: Parental Depression and Child Development

Although Yolanda and Jay completed my child development course three months before their baby was born, both agreed to return to share their reactions to birth and new parenthood with next term’s class. Two-week-old Joshua came along as well. Yolanda and Jay’s story revealed that the birth of a baby is one of the most dramatic and emotional events in human experience. Jay was present throughout Yolanda’s labor and delivery. Yolanda explained:

By morning, we knew I was in labor. It was Thursday, so we went in for my usual weekly appointment. The doctor said, yes, the baby was on the way, but it would be a while. He told us to go home and relax and come to the hospital in three or four hours. We checked in at 3 in the afternoon; Joshua arrived at 2 o’clock the next morning. When, finally, I was ready to deliver, it went quickly. A half hour or so and some good hard pushes, and there he was! His face was red and puffy, and his head was misshapen, but I thought, “Our son! I can’t believe he’s really here.”

Jay was also elated by Joshua’s birth. “I wanted to support Yolanda and to experience as much as I could. It was awesome, indescribable,” he said, holding little Joshua over his shoulder and patting and kissing him gently.

In this chapter, we explore the experience of childbirth, from both the parents’ and the baby’s point of view. Today, women in industrialized nations have many choices about where and how they give birth, and hospitals go to great lengths to make the arrival of a new baby a rewarding, family-centered event.

Joshua reaped the benefits of Yolanda and Jay’s careful attention to his needs during pregnancy. He was strong, alert, and healthy at birth. Nevertheless, the birth process does not always go smoothly. We will consider the pros and cons of medical interventions, such as pain-relieving drugs and surgical deliveries, designed to ease a difficult birth and protect the health of mother and baby. Our discussion also addresses birth complications, paying special attention to infants who experience oxygen deprivation or who are born underweight or too early.

Finally, Yolanda and Jay spoke candidly about how their lives had changed since Joshua’s arrival. “It’s exciting and wonderful,” reflected Yolanda, “but the adjustments are enormous. I wasn’t quite prepared for the intensity of Joshua’s 24-hour-a-day demands.” In the concluding sections of this chapter, we look closely at the remarkable capacities of newborns to adapt to the external world and to communicate their needs. We also consider how parents adjust to the realities of everyday life with a new baby. ■


4.1 Describe the three stages of childbirth, the baby’s adaptation to labor and delivery, and the newborn baby’s appearance.

It is not surprising that childbirth is often referred to as labor. It is the hardest physical work a woman may ever do. A complex series of hormonal changes initiates the process. As pregnancy advances, the placenta releases increasing amounts of corticotropin-releasing hormone (CRH), a hormone involved in the stress response. High levels of CRH trigger additional placental hormone adjustments that induce uterine contractions. And as CRH rises in the fetal bloodstream in the final prenatal weeks, it stimulates fetal production of the stress hormone cortisol, which promotes development of the lungs in preparation for breathing (Li et al., 2014; Vannuccini et al., 2016). An abnormal increase in maternal CRH in the second or third trimesters of pregnancy may be an important, early predictor of premature birth (Latendresse & Ruiz, 2011; Ruiz et al., 2015).

Several signs let Yolanda know that labor was near:

She occasionally felt the upper part of her uterus contract. These contractions are often called false labor or prelabor because they remain brief and unpredictable for several weeks.

About two weeks before birth, she experienced an event called lightening: Joshua’s head dropped low into her uterus. Placental hormone changes had caused her cervix to soften, and it no longer supported Joshua’s weight so easily.

When she experienced the bloody show, Yolanda knew that labor was only hours or days away. As the cervix began to open, the plug of mucus that sealed it during pregnancy was released, producing a reddish discharge. Soon after, uterine contractions became more frequent, and mother and baby entered the first of three stages of childbirth (see Figure 4.1).

Figure 4.1 The three stages of childbirth.

4.1.1 Stage 1: Dilation and Effacement of the Cervix

Stage 1 is the longest, lasting an average of 12 to 14 hours with a first birth and 4 to 6 hours with later births. Dilation and effacement of the cervix take place: As uterine contractions gradually become more frequent and powerful, they cause the cervix to open (dilate) and thin (efface), forming a clear channel from the uterus into the birth canal, or vagina. The uterine contractions that open the cervix are forceful and regular, starting at 10 to 20 minutes apart and lasting about 15 to 20 seconds each. Gradually, they get closer together, occurring every 2 to 3 minutes, and become stronger, persisting for as long as 60 seconds each.

During this stage, Yolanda could do nothing to speed up the process. Jay held her hand, provided sips of juice and water, and helped her get comfortable. Throughout the first few hours, Yolanda walked, stood, or sat upright. As the contractions became more intense, she leaned against pillows or lay on her side.

The climax of Stage 1 is a brief phase called transition, in which the frequency and strength of contractions are at their peak and the cervix opens completely. Although transition is the most uncomfortable part of childbirth, it is especially important that the mother relax. If she tenses or bears down with her muscles before the cervix is completely dilated and effaced, she may bruise the cervix and slow the progress of labor.

4.1.2 Stage 2: Delivery of the Baby

In Stage 2, which lasts about 50 minutes for a first birth and 20 minutes in later births, the infant is born. Strong contractions of the uterus continue, but the mother also feels a natural urge to squeeze and push with her abdominal muscles. As she does so with each contraction, she forces the baby down and out.

Between contractions, Yolanda dozed lightly. When the doctor announced that the baby’s head was crowning—the vaginal opening had stretched around the entire head—Yolanda felt renewed energy. She knew that soon the baby would arrive. Quickly, with several more pushes, Joshua’s forehead, nose, and chin emerged, then his upper body and trunk. The doctor held him up, wet with amniotic fluid and still attached to the umbilical cord. As air rushed into his lungs, Joshua cried. When the umbilical cord stopped pulsing, it was clamped and cut. A nurse placed Joshua on Yolanda’s chest, where she and Jay could see, touch, and gently talk to him. Then the nurse wrapped Joshua snugly to help with temperature regulation.

4.1.3 Stage 3: Birth of the Placenta

Stage 3 brings labor to an end. A few final contractions and pushes cause the placenta to separate from the wall of the uterus and be delivered in about 5 to 10 minutes. Yolanda and Jay were surprised at the large size of the thick 1½-pound red-gray organ, which had taken care of Joshua’s basic needs for the previous nine months.

4.1.4 The Baby’s Adaptation to Labor and Delivery

At first glance, labor and delivery seem like a dangerous ordeal for the baby. The strong contractions of Yolanda’s uterus exposed Joshua’s head to a great deal of pressure, and they squeezed the placenta and the umbilical cord repeatedly, temporarily reducing Joshua’s supply of oxygen.

Fortunately, healthy babies are equipped to withstand these traumas. The force of the contractions intensifies the baby’s production of stress hormones. Unlike during pregnancy, when excessive stress endangers the fetus (see Chapter 3), during childbirth high levels of infant cortisol and other stress hormones are adaptive. They help the baby withstand oxygen deprivation by sending a rich supply of blood to the brain and heart (Gluckman, Sizonenko, & Bassett, 1999). In addition, stress hormones prepare the baby to breathe by causing the lungs to absorb any remaining fluid and by expanding the bronchial tubes (passages leading to the lungs). Finally, stress hormones arouse the infant into alertness. Joshua was born wide-awake, ready to interact with the surrounding world.

4.1.5 The Newborn Baby’s Appearance

Parents are often surprised at the odd-looking newborn—a far cry from the storybook image they may have had in their minds. The average newborn is 20 inches long and 7½ pounds in weight; boys tend to be slightly longer and heavier than girls. The head is large in comparison to the trunk and legs, which are short and bowed. Proportionally, if your head were as large as that of a newborn infant, you would be balancing something about the size of a watermelon between your shoulders! This combination of a large head (with its well-developed brain) and a small body means that human infants learn quickly in the first few months of life. But unlike most other mammals, they cannot get around on their own until much later.

To accommodate the well-developed brain, a newborn’s head is large in relation to the trunk and legs. Notice the vernix on the baby’s skin, which protected it from chapping while exposed to the amniotic fluid during pregnancy.

Noctiluxx/Getty Images

Even though newborn babies may not match parents’ idealized image, some features do make them attractive. Their captivating round faces, chubby cheeks, large foreheads, and big eyes generally make adults want to pick them up and cuddle them (Luo et al., 2015).

4.1.6 Assessing the Newborn’s Physical Condition: The Apgar Scale

To assess the newborn’s physical condition quickly, doctors and nurses use the Apgar Scale. As Table 4.1 shows, a rating of 0, 1, or 2 on each of five characteristics is made at 1 minute and again at 5 minutes after birth. A combined Apgar score of 7 or better indicates that the infant is in good physical condition. If the score is between 4 and 6, the baby requires assistance in establishing breathing and other vital signs. If the score is 3 or below, the infant is in serious danger and requires emergency medical attention (Apgar, 1953). Two Apgar ratings are given because some babies have trouble adjusting at first but do quite well after a few minutes.

Table 4.1 The Apgar Scale






Color (Appearance)b

Blue body, arms, and legs

Body pink with blue arms and legs

Body, arms, and legs completely pink

Heart rate (Pulse)

No heartbeat

Under 100 beats per minute

100 to 140 beats per minute

Reflex irritability (Grimacing, sneezing, and coughing)

No response

Weak reflexive response

Strong reflexive response

Muscle tone (Activity)

Completely limp

Weak movements of arms and legs

Strong movements of arms and legs

Breathing (Respiratory effort)

No breathing for 60 seconds

Irregular, shallow breathing

Strong breathing and crying

aAs an aid for remembering these signs, note that the boldfaced first letter of the words in parentheses—Appearance, Pulse, Grimacing, Activity, and Respiratory effort—together spell Apgar.

bIt is difficult to apply the pink color criterion to babies with olive to brown skin tones. However, all newborns can be rated for the pinkish glow that results from the flow of oxygen through body tissues.

Source: Apgar, 1953.

Ask Yourself

Connect ■ Contrast the positive impact of the baby’s production of high levels of stress hormones during childbirth with the negative impact of severe maternal stress on the fetus, discussed on pages 108–109 in Chapter 3.

Apply ■ On seeing her newborn baby for the first time, Caroline exclaimed, “Why is she so out of proportion?” What observations prompted Caroline to ask this question? Explain why her baby’s appearance is adaptive.


4.2 Describe natural childbirth and home delivery, noting benefits and concerns associated with each.

Childbirth practices, like other aspects of family life, are molded by the society of which mother and baby are a part. In many village and tribal cultures, expectant mothers are well-acquainted with the childbirth process. For example, the Jarara of South America and the Pukapukans of the Pacific Islands treat birth as a vital part of daily life (Lowis & McCaffery, 2004). The Jarara mother gives birth in full view of the entire community, including small children. The Pukapukan girl is so familiar with the events of labor and delivery that she can frequently be seen playing at it. Using a coconut to represent the baby, she stuffs it inside her dress, imitates the mother’s pushing, and lets the nut fall at the proper moment.

In most nonindustrialized cultures, women are assisted—though often not by medical personnel—during labor and delivery. Among the Mende of Sierra Leone, birth attendants are appointed by the village chief and are highly respected members of their communities. They visit expectant mothers before and after a birth to provide advice, can be called to help deliver a baby at any time, and practice traditional strategies to promote delivery, including massaging the abdomen and supporting the woman in a squatting position (Dorwie & Pacquiao, 2014). In Bolivia, a Siriono mother delivers her own baby in a hammock with a crowd of women close by, who keep her company. The father cuts the umbilical cord and joins the mother in tending to the newborn for the first few days (Reed, 2005).

In Western nations, childbirth has changed dramatically over the centuries. Before the late 1800s, birth usually took place at home and was a family-centered event. The industrial revolution brought greater crowding to cities, along with new health problems. As a result, childbirth moved from home to hospital, where the health of mothers and babies could be protected (Borst, 1995). Once doctors assumed responsibility for childbirth, women’s knowledge of it declined, and relatives and friends no longer participated.

By the 1950s and 1960s, women had begun to question the medical procedures that had come to be used during labor and delivery. Many felt that routine use of strong drugs and delivery instruments had robbed them of a precious experience and was often neither necessary nor safe for the baby. Gradually, a natural childbirth movement arose in Europe and spread to North America. Its purpose was to make hospital birth as comfortable and rewarding for mothers as possible. Today, most hospitals offer birth centers that are family-centered and homelike and that encourage early contact between parents and baby.

In Sierra Leone, a new mother rests comfortably after giving birth to twins. She had her first twin at home, assisted by village birth attendants. After complications arose, the birth attendants took her to a clinic, where they collaborated with nurses in delivering her second twin. Throughout, cultural practices remained a part of this birth experience.


Freestanding birth centers also exist. They permit greater maternal control over labor and delivery, including choice of delivery positions and presence of family members and friends, as well as timely transfer to a hospital should an emergency arise. And a small number of North American women reject institutional birth entirely and choose to have their babies at home.

4.2.1 Natural, or Prepared, Childbirth

Yolanda and Jay chose natural, or prepared, childbirth—a group of techniques aimed at reducing pain and medical intervention and making childbirth a rewarding experience. Most natural childbirth programs draw on methods developed by Grantly Dick-Read (1959) in England and Fernand Lamaze (1958) in France. These physicians recognized that cultural attitudes had taught women to fear the birth experience. An anxious, frightened woman in labor tenses her muscles, heightening the pain that usually accompanies strong contractions.

As the father looks on, a mother reaches for her newborn after giving birth. A companion’s support is a vital part of natural childbirth, which is associated with shorter labors, fewer complications, and a more rewarding birth experience.

Burger/Phanie/Alamy Stock Photo

In a typical natural childbirth program, the expectant mother and a companion (a partner, relative, or friend) participate in three activities:

Classes. Yolanda and Jay attended a series of classes in which they learned about the anatomy and physiology of labor and delivery. Knowledge about the birth process reduces a mother’s fear.

Relaxation and breathing techniques. During each class, Yolanda was taught relaxation and breathing exercises aimed at counteracting the pain of uterine contractions.

Labor coach. Jay learned how to help Yolanda during childbirth by reminding her to relax and breathe, massaging her back, supporting her body, and offering encouragement and affection.

Social Support and Natural Childbirth

Social support is important to the success of natural childbirth. Mothers who are supported during labor and delivery—either by a doula (a Greek word referring to a trained lay attendant) or by a relative or friend with doula training—less often have instrument-assisted or cesarean (surgical) deliveries or need medication to control pain. Also, their babies’ Apgar scores are higher, and they are more likely to be breastfeeding at a two-month follow-up (Campbell et al., 2006, 2007; Hodnett et al., 2012; McGrath & Kennell, 2008).

The continuous rather than intermittent support of a doula during labor and delivery strengthens these benefits for mothers and babies—outcomes evident in studies conducted in both developing and developed nations and among women of diverse ethnicities (Hodnett et al., 2012). Furthermore, this aspect of natural childbirth makes Western hospital-birth customs more acceptable to women from parts of the world where assistance from family and community members is the norm (Dundek, 2006).

Look and Listen

Talk to several mothers about social supports available to them during labor and delivery. From the mothers’ perspectives, how did those supports (or lack of support) affect the birth experience?

Positions for Delivery

When natural childbirth is combined with delivery in a birth center or at home, mothers often give birth in an upright, sitting position rather than lying flat on their backs with their feet in stirrups (the traditional hospital delivery room practice). When mothers are upright, labor is slightly shorter because contractions are stronger and pushing is more effective (Kopas, 2014). The baby benefits from a richer supply of oxygen because blood flow to the placenta is increased, and fewer infant heartbeat irregularities occur. Compared with those who give birth lying on their backs, women who choose an upright position are less likely to use pain-relieving medication or to have instrument-assisted deliveries (Gupta, Hofmeyr, & Shehmar, 2012; Romano & Lothian, 2008).

In another increasingly popular method, water birth, the mother sits in a warm tub of water, which supports her weight, relaxes her, and provides her with the freedom to move into any position she finds most comfortable. Among mothers at low risk for birth complications, water birth is associated with reduced maternal stress, shorter labor, and greater likelihood of medication-free delivery than both back-lying and seated positions. As long as water birth is carefully managed by skilled health professionals, it poses no additional risk of infection or safety to mothers or babies (American Association of Birth Centers, 2014; Vanderlaan, Hall, & Lewitt, 2018).

4.2.2 Home Delivery

Home birth has always been popular in certain industrialized nations, such as England, the Netherlands, and Sweden. The number of American women choosing to have their babies at home rose during the 1970s and 1980s but remains small, at less than 1 percent (Martin et al., 2018). Although some home births are attended by doctors, many more are handled by certified nurse-midwives, who have degrees in nursing and additional training in childbirth management.

The joys and perils of home delivery are well illustrated by a story told by Don, a father of four. “Our first child was delivered in the hospital,” he said. “Even though I was present, Kathy and I found the atmosphere to be rigid and insensitive. We wanted a warmer, more personal birth environment.” With a nurse-midwife’s coaching, Don delivered their second child, Cindy, at their rural farmhouse. Three years later, when Kathy went into labor with Marnie, a heavy snowstorm prevented the midwife from reaching the house on time, so Don delivered the baby alone. The birth was difficult, and Marnie failed to breathe for several minutes. With great effort, Don revived her. The frightening memory of Marnie’s limp, blue body convinced Don and Kathy to return to the hospital to have their last child. By then, the hospital’s birth practices had changed, and the event was a rewarding one for both parents.

After a home birth, the midwife and a lay attendant provide support to the new mother. For healthy women attended by a well-trained doctor or midwife, home birth is as safe as hospital birth.


Don and Kathy’s experience raises the question: Is it just as safe to give birth at home as in a hospital? For healthy women who are assisted by a well-trained doctor or midwife, it seems so because complications rarely occur (Cheyney et al., 2014). However, if attendants are not carefully trained and prepared to handle emergencies, the likelihood of infant disability and death is high (Grünebaum et al., 2015). When mothers are at risk for any kind of complication, the appropriate place for labor and delivery is the hospital, where life-saving treatment is available.


4.3 List common medical interventions during childbirth, circumstances that justify their use, and any dangers associated with each.

Medical interventions during childbirth occur in both industrialized and nonindustrialized cultures. For example, some tribal and village societies have discovered foods, oils, and herbs that stimulate labor and have devised surgical techniques to deliver babies (Alliance of African Midwives, 2012; Jordan, 1993). Yet childbirth in North America, more so than elsewhere in the world, is a medically monitored and controlled event. Use of some medical procedures has reached epic proportions—in part because of rising rates of multiple births and other high-risk deliveries, which are associated with increased maternal age and use of fertility treatments. But births unaffected by these factors are also medicalized.

What medical techniques are doctors likely to use during labor and delivery? When are they justified, and what dangers do they pose to mothers and babies?

4.3.1 Fetal Monitoring

Fetal monitors are electronic instruments that track the baby’s heart rate during labor. An abnormal heartbeat pattern may indicate that the baby is in distress due to anoxia, or inadequate oxygen supply, and needs to be delivered immediately. Continuous fetal monitoring, which is required in most U.S. hospitals, is used in over 85 percent of U.S. births. The most popular type of monitor is strapped across the mother’s abdomen throughout labor. A second, more accurate method involves threading a recording device through the cervix and placing it directly under the baby’s scalp.

Fetal monitoring is a safe medical procedure that has saved the lives of many babies in high-risk situations. In healthy pregnancies, however, it does not reduce the already low rates of infant brain damage and death. Furthermore, most infants have some heartbeat irregularities during labor, so critics worry that fetal monitors identify many babies as in danger who, in fact, are not. Monitoring is linked to an increase in the number of instrument and cesarean (surgical) deliveries, practices we will discuss shortly (Mullins, Lees, & Brocklehurst, 2017). In addition, some women complain that the devices are uncomfortable and interfere with the normal course of labor.

Still, fetal monitors will probably continue to be used routinely in the United States, even though they are not necessary in most cases. Doctors fear that they will be sued for malpractice if they cannot show that they did everything they could to avert the death of an infant or the birth of an infant with problems.

The fetal monitor strapped across this mother’s abdomen uses ultrasound to record fetal heart rate throughout labor. In high-risk situations, fetal monitoring saves many lives. But it also may encourage unnecessary instrument and cesarean deliveries.

© BSIP SA/ALAMY Stock Photo

4.3.2 Labor and Delivery Medication

Some form of medication is used in over 60 percent of U.S. births (Declercq et al., 2014). Analgesics, drugs used to relieve pain, may be given in mild doses during labor to help a mother relax. Anesthetics are a stronger type of painkiller that blocks sensation. Currently, the most common approach to controlling pain during labor is epidural analgesia, in which a regional pain-relieving drug is delivered continuously through a catheter into a small space in the lower spine. Unlike older spinal block procedures, which numb the entire lower half of the body, epidural analgesia limits pain reduction to the pelvic region. Because the mother retains the capacity to feel the pressure of the contractions and to move her trunk and legs, she is able to push during the second stage of labor.

Although pain-relieving drugs help women cope with childbirth and enable doctors to perform essential medical interventions, they also can cause problems. Epidural analgesia, for example, weakens uterine contractions. As a result, labor is prolonged, and the chances of instrument delivery or cesarean (surgical) birth increase. And because drugs rapidly cross the placenta, exposed newborns are at risk for respiratory distress (Kumar et al., 2014). They also tend to have lower Apgar scores, to be sleepy and withdrawn, to suck poorly during feedings, and to be irritable when awake (Platt, 2014; Törnell et al., 2015). Although no confirmed long-term consequences for development exist, the negative impact of these drugs on the newborn’s adjustment supports the current trend to limit their use.

4.3.3 Instrument Delivery

Forceps, metal clamps placed around the baby’s head to pull the infant from the birth canal, have been used since the sixteenth century to speed up delivery (see Figure 4.2). A more recent instrument, the vacuum extractor, consists of a plastic cup (placed on the baby’s head) attached to a suction tube. Instrument delivery is appropriate if the mother’s pushing during the second stage of labor does not move the baby through the birth canal in a reasonable period of time.

Instrument use has declined considerably over the past three decades, partly because doctors more often deliver babies surgically when labor problems arise. Today, forceps and (more often) vacuum extractors continue to be used in about 3 percent of U.S. births (Martin et al., 2018).

Using forceps to pull the baby through most or all of the birth canal greatly increases the risk of brain damage. As a result, forceps are seldom used this way today. Low-forceps delivery (carried out when the baby is most of the way through the vagina) is associated with injury to the baby’s head and the mother’s tissues. Vacuum extractors, which have rapidly replaced forceps as the dominant instrument, are less likely to tear the mother’s tissues. Nevertheless, cup suction doubles the risk of bleeding beneath the baby’s skin and on the outside of the skull compared with nonassisted deliveries. And the risk of more serious complications, including bleeding beneath the skull and seizures (which can damage the brain), increases tenfold (Ekéus, Högberg, & Norman, 2014; Muraca et al., 2017). Consequently, neither instrument should be used when mothers can be encouraged to deliver normally and there is no special reason to hurry the birth.

4.3.4 Cesarean Delivery

A cesarean delivery is a surgical birth; the doctor makes an incision in the mother’s abdomen and lifts the baby out of the uterus. Forty years ago, cesarean delivery was rare. Since then, cesarean rates have climbed internationally, reaching 16 percent in Finland, 24 percent in New Zealand, 26 percent in Canada, 32 percent in Australia and Switzerland, and 37 percent in the United States (Martin et al., 2018; OECD, 2017c).

Cesareans have always been warranted by medical emergencies, such as Rh incompatibility, premature separation of the placenta from the uterus, or serious maternal illness or infection (for example, the herpes simplex 2 virus, which can infect the baby during a vaginal delivery). Cesareans are also justified when babies are in breech position, turned so that the buttocks or feet would be delivered first (about 1 in every 25 births). The breech position increases the chances of squeezing of the umbilical cord as the large head moves through the birth canal, thereby depriving the infant of oxygen. Head injuries are also more likely. But the infant’s exact position makes a difference. Certain breech babies fare just as well with a normal delivery as with a cesarean (Vistad et al., 2013). Sometimes the doctor can gently turn the baby into a head-down position during the early part of labor.

Figure 4.2 Instrument delivery. The pressure that must be applied to pull the infant from the birth canal with forceps can injure the baby’s head. An alternative method, the vacuum extractor, is less likely than forceps to injure the mother’s tissues. Nevertheless, risk of infant scalp injuries and internal bleeding in the eyes and skull remains.

Although previously doctors used the rule, “Once a cesarean, always a cesarean,” today many women are offered the option of a trial of labor in subsequent births, and most who attempt a vaginal birth are successful (ACOG, 2017). The recent practice of repeated cesareans, however, cannot account for the rise in cesarean deliveries in Western nations. Instead, medical control over childbirth is largely responsible. Because many needless cesareans are performed, pregnant women should ask questions about the procedure when choosing a doctor. Although the operation itself is safe, mother and baby require more time for recovery. Anesthetic may have crossed the placenta, making cesarean newborns sleepy and unresponsive and putting them at increased risk for breathing difficulties (Kotecha, Gallacher, & Kotecha, 2016; Ramachandrappa & Jain, 2008).

Ask Yourself

Connect ■ How might natural childbirth positively affect the parent–newborn relationship? Explain how your answer illustrates bidirectional influences between parent and child, emphasized in ecological systems theory.

Apply ■ Sharon, a heavy smoker, has just arrived at the hospital in labor. Which one of the medical interventions discussed in the preceding sections is her doctor justified in using? (For help in answering this question, review the prenatal effects of tobacco on pages 100–101 in Chapter 3.

Reflect ■ If you were an expectant parent, would you choose home birth? Why or why not?


4.4a Describe risks associated with oxygen deprivation and with preterm and low-birth-weight infants, along with effective interventions.

4.4b Describe factors that promote resilience in infants who survive a traumatic birth.

We have seen that some infants—in particular, those whose mothers are in poor health, do not receive good medical care, or have a history of pregnancy problems—are especially likely to experience birth complications. Inadequate oxygen, a pregnancy that ends too early, and a baby who is born underweight are serious risks to development that we have touched on many times. A baby remaining in the uterus too long is yet another risk. Let’s look at the impact of each complication on later development.

4.4.1 Oxygen Deprivation

Some years ago, I got to know 4-year-old Melinda and her mother, Judy, both of whom participated in a special program for children with disabilities at our laboratory school. Melinda has cerebral palsy, a general term for a variety of impairments in muscle coordination caused by brain damage before, during, or just after birth. The disorder can range from very mild tremors to severe crippling and intellectual disability. One out of every 500 American children has cerebral palsy. About 10 percent experienced anoxia as a result of decreased maternal blood supply during labor and delivery (Clark, Ghulmiyyah, & Hankins, 2008; McIntyre et al., 2013).

Melinda walks with a halting, lumbering gait and has difficulty keeping her balance. “Some mothers don’t know how the palsy happened,” confided Judy, “but I do. I got pregnant accidentally, and my boyfriend didn’t want to have anything to do with it. I was frightened and alone most of the time. I arrived at the hospital at the last minute. Melinda was breech, and the cord was wrapped around her neck.”

Squeezing of the umbilical cord, as in Melinda’s case, is one cause of anoxia. Another cause is placenta abruptio, or premature separation of the placenta, a life-threatening event with a high rate of infant death. Factors related to it include multiple fetuses and teratogens that cause constriction of blood vessels and abnormal development of the placenta, such as tobacco, alcohol, and cocaine (Downes, Shenassa, & Grantz, 2017). Just as serious is placenta previa, a condition caused by implantation of the blastocyst so low in the uterus that the placenta covers the cervical opening. As the cervix dilates and effaces in the third trimester, part of the placenta may detach. Women who have had previous cesareans or who are carrying multiple fetuses are at increased risk (Trønnes et al., 2014). Although placenta abruptio and placenta previa occur in only 1 to 2 percent of births, they can cause severe hemorrhaging, which requires that an emergency cesarean be performed.

Treatment for this newborn, who experienced oxygen deprivation, includes a cooling water blanket to lower the baby’s body temperature, which helps prevent brain damage.

© Andrew Shurtleff/The Daily Progress/AP Images

In still other instances, the birth seems to go along all right, but the baby fails to start breathing within a few minutes. Healthy newborns can survive periods of little or no oxygen longer than adults can; they reduce their metabolic rate, thereby conserving the limited oxygen available. Nevertheless, brain damage is likely if regular breathing is delayed more than 10 minutes (Rennie & Rosenbloom, 2011). Can you think of other possible causes of oxygen deprivation that you learned about as you studied prenatal development and birth?

After initial brain injury from anoxia during labor or delivery, another phase of cell death can occur several hours later and last for several days or longer. Hypothermia treatment, by placing anoxic newborns in a head-cooling device shortly after birth for 72 hours, substantially reduces this secondary brain damage (detected through brain scans) (Hoehn et al., 2008). Another alternative—whole-body cooling in which anoxic newborns are laid on a precooled water blanket—leads to an impressive reduction in death and disability rates during the first two years (Allen, 2014).

Still, nearly half of newborns treated with hypothermia display persisting motor and cognitive deficits. Those who experienced mild to moderate anoxia often improve over time (Azzopardi et al., 2016; Pappas & Korzeniewski, 2016). In Melinda’s case, her physical disability was permanent, but with warm, stimulating intervention services, she was just slightly behind in cognitive and language skills as a preschooler. When development is severely impaired, the anoxia was likely extreme. Perhaps it was caused by prenatal insult to the respiratory system, or it may have happened because the newborn’s lungs were not yet mature enough to breathe.

For example, infants born more than six weeks early commonly have respiratory distress syndrome (otherwise known as hyaline membrane disease). Their tiny lungs are so poorly developed that the air sacs collapse, causing serious breathing difficulties. Although mechanical respirators keep many such infants alive, some suffer permanent brain damage from lack of oxygen, and in other cases their delicate lungs are harmed by the treatment itself. As we will see next, respiratory distress syndrome is just one of many risks for babies born too soon.

4.4.2 Preterm and Low-Birth-Weight Infants

Janet, nearly six months pregnant, and her husband, Rick, boarded a flight in Hartford, Connecticut, on their way to a vacation in Hawaii. During a stopover in San Francisco, Janet told Rick she was bleeding. Rushed to a hospital, she gave birth to Keith, who weighed less than 1½ pounds. Delivered 23 weeks after conception, he had barely reached the age of viability (see page 95 in Chapter 3).

During Keith’s first month, he experienced one crisis after another. Three days after birth, an ultrasound suggested that fragile blood vessels feeding Keith’s brain had hemorrhaged, a complication that can cause brain damage. Within three weeks, Keith had surgery to close a heart valve that seals automatically in full-term babies. Keith’s immature immune system made infections difficult to contain. Repeated illnesses and the drugs used to treat them caused permanent hearing loss. Keith also had respiratory distress syndrome and breathed with the help of a respirator. Soon evidence of lung damage emerged. More than three months of hospitalization passed before Keith’s rough course of complications and treatment eased.

Babies born three weeks or more before the end of a full 38-week pregnancy or who weigh less than 5½ pounds (2,500 grams) have for many years been referred to as “premature.” Birth weight is the best available predictor of infant survival and healthy development. Many newborns who weigh less than 3½ pounds (1,500 grams) experience persisting difficulties, an effect that becomes stronger as length of pregnancy and birth weight decrease (see Figure 4.3) (Bolisetty et al., 2006; Wilson-Ching et al., 2013). Brain abnormalities, frequent illness, inattention, overactivity, sensory impairments, poor motor coordination, language delays, low intelligence test scores, deficits in school learning, and emotional and behavior difficulties are some of the problems that persist through childhood and adolescence and into adulthood (Breeman et al., 2017; Lemola, 2015; Mathewson et al., 2017).

About 11 percent of American infants are born early, and 8 percent are born underweight. The two risk factors often co-occur, and they can strike unexpectedly, as Keith’s case illustrates. But the problem is highest among poverty-stricken women (Martin et al., 2018). These mothers, as indicated in Chapter 3, are more likely to be under stress, undernourished, and exposed to other harmful environmental influences—factors strongly linked to low birth weight. In addition, they often do not receive adequate prenatal care.

Figure 4.3 Rates of infant survival and child disabilities by length of pregnancy. In a follow-up of more than 2,300 babies born between 23 and 28 weeks gestation, the percentage who survived decreased and the percentage who displayed moderate to severe disabilities (assessed during the preschool years) increased with reduced length of pregnancy. Severe disabilities included cerebral palsy (unlikely to ever walk), severely delayed mental development, deafness, and blindness. Moderate disabilities included cerebral palsy (able to walk with assistance), moderately delayed mental development, and hearing impairments partially correctable with a hearing aid. (Adapted from Bolisetty et al., 2006.)

African-American infants are especially vulnerable to early and underweight birth: They have about twice the rates of white and Hispanic infants, even after accounting for SES and other potentially contributing factors, such as single parenthood and young maternal age (Martin et al., 2018). Researchers suspect that African-American expectant mothers’ greater exposure to multiple chronic stressors, such as job strain (long hours at tiring work), crime-ridden neighborhoods, crowded living conditions, and prejudice and discrimination, is involved (Dunkel-Shetter, 2011; Dunkel-Shetter & Lobel, 2012). Many studies confirm, for example, that African-American women’s experience of race-related stressors—biased treatment at school, at work, or in access to housing—predict lower birth weight in their infants (Black, Johnson, & VanHoose, 2015).

Furthermore, low birth weight is often transmitted across generations: Women who were underweight at birth themselves are nearly twice as likely as other women to bear an underweight baby (Collins, Rankin, & David, 2011; Ncube et al., 2017). The possible causes are diverse: They may be genetic, environmental, or epigenetic—for example, excessive prenatal stress may impair offspring’s lifelong capacity to manage stress (see page 109 in Chapter 3). When a daughter becomes pregnant, she exposes her fetus to severe emotional stress and its negative consequences.

Recall from Chapter 2 that prematurity is also common in multiple births. About 55 percent of twins and more than 90 percent of triplets are born early and low birth weight (Martin et al., 2018). Because space inside the uterus is restricted, multiples gain less weight than singletons in the second half of pregnancy.

Preterm Versus Small-for-Date Infants

Although preterm and low-birth-weight infants face many obstacles to healthy development, most go on to lead normal lives; about half of those born at 23 to 24 weeks gestation and weighing only a couple of pounds at birth have no disability (refer again to Figure 4.3). To better understand why some babies do better than others, researchers divide them into two groups. Preterm infants are born several weeks or more before their due date. Although they are small, their weight may still be appropriate, based on time spent in the uterus. Small-for-date infants are below their expected weight considering the length of the pregnancy. Some small-for-date infants are actually full-term. Others are preterm babies who are especially underweight.

Small-for-date infants, especially those who are also preterm, usually have more serious problems. During the first year, they are more likely to die, catch infections, and show evidence of brain damage. By middle childhood, they are smaller in stature, have lower intelligence test scores, are less attentive, achieve more poorly in school, and are socially immature (Katz et al., 2013; Tsai et al., 2015; Wilson-Ching et al., 2013).

Small-for-date infants probably experienced inadequate nutrition before birth. Perhaps their mothers did not eat properly, the placenta did not function normally, or the babies themselves had defects that prevented them from growing as they should. In some of these babies, an abnormally functioning placenta permitted ready transfer of stress hormones from mother to fetus. Consequently, small-for-date infants are especially likely to suffer from neurological impairments that permanently weaken their capacity to manage stress (Osterholm, Hostinar, & Gunnar, 2012). Severe stress, in turn, heightens their susceptibility to later physical and psychological health problems.

Even among preterm newborns whose weight is appropriate for length of pregnancy, just 7 to 14 more days—from 34 to 35 or 36 weeks—greatly reduces rates of illness, costly medical procedures, and lengthy hospital stays (although they need greater medical intervention than full-term babies) (Ananth, Friedman, & Gyamfi-Bannerman, 2013). In longitudinal follow-ups of thousands of births, infants born even 1 or 2 weeks early showed slightly lower kindergarten cognitive and language scores and third-grade reading and math scores than agemates who experienced a full-length prenatal period (Noble et al., 2012; Woythaler et al., 2015). These outcomes persisted even after controlling for other factors linked to achievement, such as birth weight and SES. Yet doctors often induce births several weeks preterm, under the misconception that these babies are developmentally “mature.”

Consequences for Caregiving

Imagine a scrawny, thin-skinned infant only a little larger than the size of your hand. You try to play with the baby by stroking and talking softly, but he is sleepy and unresponsive. When you feed him, he sucks poorly. During the short, unpredictable periods in which he is awake, he is usually irritable.

The appearance and behavior of preterm infants—scrawny and thin-skinned, sleepy and unresponsive, irritable when briefly awake—can lead parents to be less sensitive in caring for them. Compared with full-term infants, preterm babies—especially those who are very ill at birth—are less often held close, touched, and talked to gently. At times, mothers of these infants resort to interfering pokes and verbal commands in an effort to obtain a higher level of response from them (Feldman, 2007b; Forcada-Guex et al., 2006). This may explain why preterm babies as a group are at risk for child abuse.

Distressed, emotionally reactive preterm infants are particularly susceptible to the effects of parenting quality: Among a sample of preterm 9-month-olds, the combination of infant negativity and angry or intrusive parenting yielded the highest rates of behavior problems at 2 years of age. But with warm, sensitive parenting, distressed preterm babies’ rates of behavior problems were the lowest (Poehlmann et al., 2011).

When preterm infants are born to isolated, poverty-stricken mothers who cannot provide good nutrition, health care, and parenting, the likelihood of unfavorable outcomes increases. In contrast, parents with stable life circumstances and social supports usually can overcome the stresses of caring for a preterm infant (Ment et al., 2003). In these cases, even sick preterm babies have a good chance of catching up in development by middle childhood.

These findings suggest that how well preterm babies develop has a great deal to do with the parent–child relationship. Consequently, interventions directed at supporting both sides of this tie are more likely to help these infants recover.

Interventions for Preterm Infants

A preterm baby is cared for in a special Plexiglas-enclosed bed called an isolette. Temperature is carefully controlled because these infants cannot yet regulate their own body temperature effectively. To help protect the baby from infection, air is filtered before it enters the isolette. When a preterm infant is fed through a stomach tube, breathes with the aid of a respirator, and receives medication through an intravenous needle, the isolette can be very isolating indeed! Physical needs that otherwise would lead to close contact and other human stimulation are met mechanically.

Special Infant Stimulation

In proper doses, certain kinds of stimulation can help preterm infants develop. In some intensive care nurseries, preterm babies can be seen rocking in suspended hammocks, lying on waterbeds designed to replace the gentle motion they would have received while still in the mother’s uterus, or listening to soft music—experiences that promote faster weight gain, improved breathing, more predictable sleep patterns, and greater alertness (Cramer et al., 2018; Marshall-Baker, Lickliter, & Cooper, 1998; Schwilling et al., 2014). In one experiment, extremely preterm newborns, born between the 25th and 32nd prenatal weeks, were exposed either to recordings of their mother’s voice and heartbeat for several hours each day or to routine hospital noise. At age 1 month, an ultrasound revealed that auditory areas of the brain had grown substantially larger in the maternal sounds group (see Figure 4.4) (Webb et al., 2015). Listening to womblike, familiar rhythmic maternal sounds, as opposed to the unpredictable din of hospital equipment, promoted brain development.

Touch is an especially important form of stimulation. In baby animals, touching the skin releases certain brain chemicals that support physical growth—effects believed to occur in humans as well. When preterm infants were gently massaged several times each day in the hospital, they gained weight faster and, at the end of the first year, were more advanced in mental and motor development than preterm babies not given this stimulation (Álvarez et al., 2017; Field, Hernandez-Reif, & Freedman, 2004).

Figure 4.4 Listening to mother’s voice and heartbeat enhances brain development in extremely preterm newborns. Infants born between the 25th and 32nd prenatal weeks were randomly assigned to hear either recordings of their mother’s voice and heartbeat for several hours a day or routine, unpatterned hospital noise. After a month’s exposure in the intensive care nursery, ultrasound measures showed that the left and right cerebral auditory areas were substantially thicker in the maternal sounds group than the hospital noise group. In addition to highlighting an effective intervention, the results suggest that exposure to soft, rhythmic maternal sounds during pregnancy enhances early brain growth. (Based on Webb et al., 2015.)

In developing countries where hospitalization is not always possible, skin-to-skin “kangaroo care” is the most readily available intervention for promoting the survival and development of preterm babies. It involves placing the infant in a vertical position between the mother’s breasts or next to the father’s chest (under the parent’s clothing) so the parent’s body functions as a human incubator. Kangaroo care offers fathers a unique opportunity to increase their involvement in caring for the preterm newborn.

Kangaroo skin-to-skin contact fosters improved oxygenation of the baby’s body, temperature regulation, sleep, breastfeeding, alertness, and infant survival (Conde-Agudelo, Belizan, & Diaz-Rossello, 2011; Kaffashi et al., 2013). In addition, the kangaroo position provides the baby with gentle stimulation of all sensory modalities: hearing (through the parent’s voice), smell (through proximity to the parent’s body), touch (through skin-to-skin contact), and vision (through the upright position). Mothers and fathers practicing kangaroo care feel more confident about caring for their fragile babies, interact more sensitively and affectionately, and feel more attached to them (Dodd, 2005; Feldman, 2007a).

A mother uses skin-to-skin “kangaroo care” to warm and gently stimulate her preterm newborn at a hospital in Manilla, the Philippines. In developing countries, kangaroo care may be the most readily available intervention for promoting the survival of preterm and underweight babies. In Western nations, kangaroo care is often used as a supplement to hospital intensive care.


Together, these factors may explain why preterm babies given many hours of kangaroo care in their early weeks, compared to those given little or no such care, are more likely to explore novel toys and score higher on measures of mental and motor development during the first year and beyond (Bera et al., 2014; Feldman, 2007a). In an investigation that followed children born preterm until age 10, those who had experienced two weeks of kangaroo care after birth, compared with matched controls given standard incubator care, displayed a more adaptive cortisol stress response, better organized sleep, more favorable mother–child interaction, and enhanced cognitive development. Favorable neurobiological and cognitive outcomes persisted through middle childhood (Feldman, Rosenthal, & Eidelman, 2014). Because of its diverse benefits, most hospital nurseries in Western nations offer kangaroo care to parents and preterm newborns.

Training Parents in Infant Caregiving Skills

Interventions that support parents of preterm infants generally teach them how to recognize and respond to the baby’s needs. For parents with the economic and personal resources to care for a preterm infant, just a few sessions of coaching in recognizing and responding to the baby’s needs are linked to enhanced parent–infant interaction, reduced infant crying and improved sleep, more rapid language development in the second year, and steady gains in mental test performance that equal those of full-term children by middle childhood (Achenbach, Howell, & Aoki, 1993; Newnham, Milgrom, & Skouteris, 2009).

When preterm infants live in stressed, economically disadvantaged households, long-term intensive intervention is necessary (Guralnick, 2012). In the Infant Health and Development Program, preterm babies born into poverty received a comprehensive intervention aimed at promoting all aspects of their development. It combined medical follow-up, weekly home visits in which mothers received training in infant care and everyday problem solving, and cognitively stimulating child care from 1 to 3 years of age. More than four times as many intervention children as no-intervention controls (39 versus 9 percent) were within normal range at age 3 in intelligence, psychological adjustment, and physical growth (Bradley et al., 1994). In addition, mothers in the intervention group were more affectionate and more often encouraged play and cognitive mastery in their children—one reason their 3-year-olds may have been developing so favorably (McCarton, 1998).

At ages 5 and 8, children who had attended the child-care program regularly—for more than 350 days over the three-year period—continued to show better intellectual functioning. The more they attended, the higher they scored, with greater gains among those whose birth weights were higher—between 4½ and 5½ pounds (2,001 to 2,500 grams) (see Figure 4.5). In contrast, children who attended only sporadically gained little or even lost ground (Hill, Brooks-Gunn, & Waldfogel, 2003). A follow-up at age 18 revealed persisting benefits for the higher-birth-weight participants: They remained advantaged over controls in academic achievement, and they also engaged in fewer risky behaviors such as unprotected sexual activity and alcohol and drug use (McCormick et al., 2006).

These findings confirm that babies who are both preterm and economically disadvantaged require intensive intervention. And special strategies, such as extra adult–child interaction both at home and in infant–toddler and early childhood programs, may be necessary to achieve lasting changes in children with the lowest birth weights.

Nevertheless, even the best environments cannot always overcome the enormous biological risks associated with being born extremely preterm and underweight. Think back to Keith, the very sick baby you met at the beginning of this section. Despite advanced medical technology and new ways of helping parents, most infants born as early and with as low a birth weight as Keith either die or end up with serious disabilities (refer again to Figure 4.5). Six months after he was born, Keith died without ever having left the hospital.

Although Keith’s premature birth was unavoidable, the high rate of underweight babies in the United States—one of the worst in the industrialized world—can be greatly reduced by improving the health and social conditions described in the Cultural Influences box on page 132. Fortunately, today we can save many preterm babies, but an even better course of action would be to prevent this serious threat to infant survival and development before it happens.

Figure 4.5 Influence of intensity of early intervention for low-income, preterm babies on intellectual functioning at age 8. Infants born preterm received cognitively stimulating child care from 1 through 3 years of age. Those who attended the program sporadically gained little in intellectual functioning (heavier-weight babies) or lost ground (lighter-weight babies). The more often children attended, the greater their intellectual gains. Heavier babies consistently gained more than light babies. But boosting the intensity of intervention above 400 days led to a dramatic increase in the performance of the light-weight group. (Adapted from Hill, Brooks-Gunn, & Waldfogel, 2003.)

4.4.3 Birth Complications, Parenting, and Resilience

In the preceding sections, we considered major birth complications. Now let’s try to put the evidence together. Can any general principles help us understand how infants who survive a traumatic birth are likely to develop? A landmark study carried out in Hawaii provides answers to this question.

In 1955, Emmy Werner and Ruth Smith began to follow the development of nearly 700 infants on the island of Kauai who experienced either mild, moderate, or severe birth complications. Each was matched, on the basis of SES and ethnicity, with a healthy newborn (Werner & Smith, 1982). The children were monitored in childhood and adolescence and at ages 32 and 40 in adulthood.

Findings revealed that the likelihood of long-term difficulties increased if birth trauma was severe. Among participants with mild to moderate birth complications, those growing up in stable families with sensitive, involved parenting fared almost as well on measures of intelligence and psychological adjustment as those with no birth complications. Children exposed to poverty, family disorganization, and mentally ill parents often developed serious learning difficulties, behavior problems, and emotional disturbance.

The Kauai study tells us that as long as birth injuries are not overwhelming, a supportive home can restore children’s development. But the most intriguing cases in this study were the handful of exceptions. A few children with both fairly serious birth complications and troubled family environments grew into competent adults who fared as well as controls in physical and mental health and vocational attainment. Werner and Smith found that these children relied on factors outside the family and within themselves to overcome stress. Some had attractive personalities—cheerfulness, agreeableness, and sociability—that drew positive responses from relatives, neighbors, and peers. In other instances, a grandparent, aunt, uncle, or babysitter provided the needed emotional support (Werner, 2001, 2005; Werner & Smith, 1992).

Do these outcomes remind you of the characteristics of resilient children, discussed in Chapter 1? The Kauai study and other similar investigations reveal that the impact of early biological risks often wanes as children’s personal characteristics and social experiences contribute increasingly to their functioning (Werner, 2013). In sum, when the overall balance of life events tips toward the favorable side, children with serious birth problems can develop successfully. And when negative factors outweigh positive ones, even a sturdy newborn can become a lifelong casualty.

Cultural InfluencesA Cross-National Perspective on Health Care and Other Policies for Parents and Newborn Babies

Infant mortality—the number of deaths in the first year of life per 1,000 live births—is an index used around the world to assess the overall health of a nation’s children. Although the United States has the most up-to-date health-care technology in the world, it has made less progress in reducing infant deaths than many other countries. Over the past three decades, it has slipped in the international rankings, from seventh in the 1950s to thirty-ninth in 2018 (see Figure 4.6). Members of America’s poor ethnic minorities are at greatest risk, with African-American infants more than twice as likely as white infants to die in the first year of life (U.S. Census Bureau, 2018b).

Neonatal mortality, the rate of death within the first month of life, accounts for 67 percent of the infant death rate in the United States. Two factors are largely responsible for neonatal mortality. The first is serious physical defects, most of which cannot be prevented. The percentage of babies born with physical defects is about the same in all ethnic and income groups. The second leading cause of neonatal mortality is low birth weight, which is largely preventable.

Widespread poverty and inadequate health-care programs for mothers and young children are largely responsible for these trends. In addition to providing government-sponsored health-care benefits to all citizens, each country in Figure 4.6 that outranks the United States in infant survival takes extra steps to make sure that pregnant mothers and babies have access to good nutrition, high-quality medical care, and social and economic supports that promote effective parenting.

For example, all Western European nations guarantee women a certain number of prenatal visits at very low or no cost. After a baby is born, a health professional routinely visits the home to provide counseling about infant care and to arrange continuing medical services. Home assistance is especially extensive in the Netherlands (Lamkaddem et al., 2014). For a token fee, each mother is granted a specially trained maternity helper, who assists with infant care, shopping, housekeeping, meal preparation, and the care of other children for 8 to 10 days after delivery.

Paid, job-protected employment leave is another vital societal intervention for new parents. Canadian mothers are eligible for 15 weeks maternity leave at 55 percent of prior earnings (up to a maximum of $413 per week), and Canadian mothers or fathers can take an additional 35 weeks of parental leave at the same rate. Sweden has the most generous parental leave program in the world. Mothers can begin maternity leave 60 days prior to expected delivery and extend it to 6 weeks after birth; fathers are granted two weeks of birth leave. In addition, either parent can take full leave for 15 months at 80 percent of prior earnings, followed by an additional three months at a modest flat rate. Each parent is also entitled to another 18 months of unpaid leave. Even economically less well-off nations provide parental leave benefits. In Bulgaria, new mothers are granted 11 months paid leave, and fathers receive 3 weeks (Addati, Cassirer, & Gilchrist, 2014).

Yet in the United States, the federal government mandates only 12 weeks of unpaid leave for employees in companies with at least 50 workers. Most women, however, work in smaller businesses, and many of those who work in large enough companies cannot afford to take unpaid leave. And because of financial pressures, many new mothers who are eligible for unpaid work leave take far less than 12 weeks. Similarly, though paternal leave—especially, 2 weeks or more—predicts fathers’ increased involvement in child care and is linked to improved cognitive development in the early years, fathers typically take less than 10 days or none at all (Huerta et al., 2013).


Figure 4.6 Infant mortality in 39 nations. Despite its advanced health-care technology, the United States ranks poorly. It is thirty-ninth in the world, with a death rate of 5.7 infants per 1,000 births. (Based on U.S. Census Bureau, 2018b.)

In 2002, California became the first state to guarantee a mother or father paid leave—up to 6 weeks at half salary, regardless of the size of the company. Since then, the District of Columbia, Hawaii, New Jersey, New York, Rhode Island, Washington, and the territory of Puerto Rico have passed similar legislation.

Nevertheless, 6 weeks of childbirth leave (the norm in the United States) is not enough. Leaves of 6 to 8 weeks or less are linked to increased maternal anxiety, depression, sense of role overload (conflict between work and family responsibilities), and negative interactions with the baby. A leave of 12 weeks or more predicts favorable maternal physical and mental health, supportive marital interaction, and sensitive caregiving (Aitken et al., 2015; Feldman, Sussman, & Zigler, 2004). Single women and their babies are most hurt by the absence of a generous national paid-leave policy. These mothers, who are usually the sole source of support for their families, can least afford to take time from their jobs.

A Swedish father takes advantage of his country’s generous parental leave program to care for and bond with his baby. Paternal leave of 2 weeks or more is linked to improved cognitive development in the early years.


In countries with low infant mortality rates, expectant parents need not wonder how they will access essential resources for supporting their baby’s development. The powerful impact of universal, high-quality health care; generous parental leave; and other social services on maternal and infant well-being provides strong justification for these policies. Responding to these findings, the U.S. Affordable Care Act provides generous grants to the states to cover the cost of evidence-based home-visiting programs that provide comprehensive services to mothers, infants, and young children in high-risk families.

Ask Yourself

Connect ■ List factors discussed in this chapter and in Chapter 3 that increase the chances of an infant being born underweight. How many of these factors could be prevented by better health care for expectant mothers?

Apply ■ Cecilia and Anna each gave birth to a 3-pound baby seven weeks preterm. Cecilia is single and on welfare. Anna and her husband are happily married and earn a good income. Plan an intervention appropriate for helping each baby develop.

Reflect ■ Many people object to the use of extraordinary medical measures to save extremely low-birth-weight babies because of their high risk for serious developmental problems. Do you agree or disagree? Explain.


4.5a Describe the newborn baby’s reflexes and states of arousal, including sleep characteristics and ways to soothe a crying baby.

4.5b Describe the newborn baby’s sensory capacities.

4.5c Explain the usefulness of neonatal behavioral assessment.

Newborn infants have a remarkable set of capacities that are crucial for survival and for evoking adult attention and care. In relating to the physical and social world, babies are active from the very start.

4.5.1 Reflexes

A reflex is an inborn, automatic response to a particular form of stimulation. Reflexes are the newborn baby’s most obvious organized patterns of behavior. As Jay placed Joshua on a table in my classroom, we saw several. When Jay bumped the side of the table, Joshua reacted by flinging his arms wide and bringing them back toward his body. As Yolanda stroked Joshua’s cheek, he turned his head in her direction. When she put her finger in Joshua’s palm, he grabbed on tightly. Look at Table 4.2 and see if you can name the newborn reflexes that Joshua displayed. Let’s consider the meaning and purpose of these curious behaviors.

Adaptive Value of Reflexes

Some reflexes have survival value. The rooting reflex helps a breastfed baby find the mother’s nipple. Babies display it only when hungry and touched by another person, not when they touch themselves (Rochat & Hespos, 1997). At birth, babies adjust their sucking pressure to how easily milk flows from the nipple (Craig & Lee, 1999). And if sucking were not automatic, our species would be unlikely to survive for a single generation! The swimming reflex helps a baby who is accidentally dropped into water stay afloat, increasing the chances of retrieval by the caregiver.

Other reflexes probably helped babies survive during our evolutionary past. For example, the Moro, or “embracing,” reflex is believed to have helped infants cling to their mothers when they were carried about all day. If the baby happened to lose support, the reflex caused the infant to embrace and, along with the palmar grasp reflex (so strong during the first week that it can support the baby’s entire weight), regain its hold on the mother’s body. Another conjecture is that the Moro embracing motion signals the caregiver to pick up and comfort a startled infant (Rousseau et al., 2017).

Table 4.2 Some Newborn Reflexes




Age of Disappearance


Eye blink

Shine bright light at eyes or clap hand near head.

Infant quickly closes eyelids.


Protects infant from strong stimulation


Stroke cheek near corner of mouth.

Head turns toward source of stimulation.

3 weeks (becomes voluntary head turning at this time)

Helps infant find the nipple


Place finger in infant’s mouth.

Infant sucks finger rhythmically.

Replaced by voluntary sucking after 4 months

Permits feeding


Occurs when infant is face down in pool of water.

Baby paddles and kicks in swimming motion.

4–6 months

Helps infant survive if dropped into water


Hold infant horizontally on back and let head drop slightly, or produce a sudden loud sound against surface supporting infant.

Infant makes an “embracing” motion by arching back, extending legs, throwing arms outward, spreading fingers, and then bringing arms in toward the body.

6 months

In human evolutionary past, may have helped infant cling to caregiver or (through extension of arms) signal caregiver to pick up baby

Palmar grasp

Place finger in infant’s hand and press against palm.

Spontaneous grasp of finger

3–4 months

Prepares infant for voluntary grasping

Tonic neck

Turn baby’s head to one side while infant is lying awake on back.

Infant lies in a “fencing position.” One arm is extended in front of eyes on side to which head is turned; other arm is flexed.

4 months

May prepare infant for voluntary reaching


Hold infant under arms and permit bare feet to touch a flat surface.

Infant lifts one foot after another in stepping response.

Replaced by voluntary walking at end of the first year

Prepares infant for voluntary walking


Stroke sole of foot from toe toward heel.

Toes fan out and curl as foot twists in.

8–12 months


aPlacing infants in a pool of water is dangerous. See discussion on page 136 in this section.

Sources: Knobloch & Pasamanick, 1974; Rousseau et al., 2017; Thelen, Fisher, & Ridley-Johnson, 1984.

Several reflexes help parents and infants establish gratifying interaction. A baby who successfully finds the nipple, sucks easily during feedings, grasps when her hand is touched, or induces the caregiver to pick her up encourages parents to respond lovingly and feel competent as caregivers. Reflexes that help infants control distress can also aid parents in comforting the baby. For example, on outings with Joshua, Yolanda brought along a pacifier. If he became fussy, sucking helped quiet him until she could feed, change, or hold him.

In the Moro reflex, loss of support or a sudden loud sound causes the baby to arch her back, extend her arms outward, and then bring them in toward her body.


Reflexes and the Development of Motor Skills

A few reflexes form the basis for complex motor skills that will develop later. For example, the tonic neck reflex may prepare the baby for voluntary reaching. When infants lie on their backs in this “fencing position,” they naturally gaze at the hand in front of their eyes. The reflex may encourage them to combine vision with arm movements and, eventually, reach for objects.

The palmar grasp reflex is so strong during the first week after birth that many infants can use it to support their entire weight.


Certain reflexes—such as the palmar grasp, swimming, and stepping—drop out early, but the motor functions involved are renewed later. The stepping reflex, for example, looks like a primitive walking response. Around 2 months, it declines as infants increasingly relax their limbs, flexing their legs at the hip and knees when lowered onto a flat surface, which inhibits stepping. But if babies are held upright in the air, the reflex is clearly evident and persists, over time being integrated into independent walking (Barbu-Roth et al., 2015). Furthermore, when stepping is exercised regularly, babies make more reflexive stepping movements and are likely to walk several weeks earlier than if stepping is not practiced (Zelazo et al., 1993). However, there is no special need for infants to practice the stepping reflex because all typically developing babies walk in due time.

In the tonic neck reflex, infants lie on their backs in a “fencing position,” which may help prepare them for voluntary reaching.


When held upright under the arms, newborn babies show reflexive stepping movements.


In the case of the swimming reflex, trying to build on it is risky. Although young infants placed in a swimming pool will paddle and kick, they swallow large amounts of water. This lowers the sodium concentration in the baby’s blood, which can cause brain swelling and seizures. Despite this remarkable reflex, swimming lessons are best postponed until at least 3 years of age.

The Importance of Assessing Newborn Reflexes

Look at Table 4.2 again, and you will see that most newborn reflexes disappear during the first six months. Researchers believe that this is due to a gradual increase in voluntary control over behavior as the cerebral cortex develops.

Pediatricians test reflexes carefully, especially if a newborn has experienced birth trauma, because reflexes can reveal the health of the baby’s nervous system. Weak or absent reflexes, overly rigid or exaggerated reflexes, and reflexes that persist beyond the point in development when they should normally disappear can signal brain damage (Schott & Rossor, 2003). However, individual differences in reflexive responses exist that are not cause for concern. An observer must assess reflexes along with other infant attributes to accurately distinguish typical from atypical central nervous system functioning.

4.5.2 States

Throughout the day and night, newborn infants move in and out of the five states of arousal, or degrees of sleep and wakefulness, described in Table 4.3. During the first month, these states alternate frequently. The most fleeting is quiet alertness, which usually moves quickly toward fussing and crying. Much to the relief of their fatigued parents, newborns spend the greatest amount of time asleep—about 16 to 18 hours a day. And even those who are as much as 8 weeks preterm are responsive to regular periods of darkness and light in their surroundings, increasingly sleeping more at night than during the day over the early weeks (Figueiredo et al., 2016; Guyer et al., 2015). Nevertheless, young babies’ sleep–wake cycles are affected more by fullness–hunger than by darkness–light (Davis, Parker, & Montgomery, 2004).

4.However, striking individual differences in daily rhythms exist that affect parents’ attitudes toward and interactions with the baby. A few newborns sleep for long periods, increasing the energy their well-rested parents have for sensitive, responsive care. Other babies wake frequently and cry often, and their parents must exert great effort to soothe them. If these parents do not succeed, they may feel less competent and less positive toward their infant. Babies who spend more time alert probably receive more social stimulation and opportunities to explore and, therefore, may have a slight advantage in cognitive development.

Table 4.3 Infant States of Arousal



Daily Duration in Newborn

Regular, or NREM, sleep

The infant is at full rest and shows little or no body activity. The eyelids are closed, no eye movements occur, the face is relaxed, and breathing is slow and regular.

8–9 hours

Irregular, or REM, sleep

Gentle limb movements, occasional stirring, and facial grimacing occur. Although the eyelids are closed, occasional rapid eye movements can be seen beneath them. Breathing is irregular.

8–9 hours


The infant is either falling asleep or waking up. Body is less active than in irregular sleep but more active than in regular sleep. The eyes open and close; when open, they have a glazed look. Breathing is even but somewhat faster than in regular sleep.


Quiet alertness

The infant’s body is relatively inactive, with eyes open and attentive. Breathing is even.

2–3 hours

Waking activity and crying

The infant shows frequent bursts of uncoordinated body activity. Breathing is very irregular. Face may be relaxed or tense and wrinkled. Crying may occur.

1–4 hours

Source: Wolff, 1966

As with adults, sleep contributes to babies’ learning and memory. In two studies, eye-movement responses and brain-wave recordings revealed that sleeping newborns readily learned that a tone would be followed by a puff of air to the eye (Fifer et al., 2010; Tarullo et al., 2015). Because young infants spend so much time sleeping, the capacity to learn about external stimuli during sleep may be essential for adaptation to their surroundings.

Of the states listed in Table 4.3, the two extremes—sleep and crying—have been of greatest interest to researchers. Each tells us something about normal and abnormal early development.


Observing Joshua as he slept, Yolanda and Jay wondered why his eyelids and body twitched and his rate of breathing varied. Sleep is made up of at least two states. During irregular, or rapid-eye-movement (REM), sleep, brain-wave activity is remarkably similar to that of the waking state. The eyes dart beneath the lids; heart rate, blood pressure, and breathing are uneven; and slight body movements occur. The expression “sleeping like a baby” was probably not meant to describe this state! In contrast, during regular, or non-rapid-eye-movement (NREM), sleep, the body is almost motionless, and heart rate, breathing, and brain-wave activity are slow and even.

Like children and adults, newborns alternate between REM and NREM sleep. However, they spend far more time in the REM state than they ever will again. REM sleep accounts for 50 percent of the newborn baby’s sleep time. By 3 to 5 years, it has declined to an adultlike level of 20 percent (Korotchikova et al., 2016; Louis et al., 1997).

Why do young infants spend so much time in REM sleep? In older children and adults, the REM state is associated with dreaming. Babies probably do not dream, at least not in the same way we do. But researchers believe that the stimulation of REM sleep is vital for growth of the central nervous system (Tarullo, Balsam, & Fifer, 2011). Young infants seem to have a special need for this stimulation because they spend little time in an alert state, when they can get input from the environment. In support of this idea, the percentage of REM sleep is especially great in the fetus and in preterm babies, who are even less able than full-term newborns to take advantage of external stimulation (Peirano, Algarin, & Uauy, 2003).

Because newborn babies’ normal sleep behavior is organized and patterned, observations of sleep states can help identify central nervous system abnormalities. Infants who are brain-damaged or who have experienced birth trauma often have disturbed REM–NREM sleep cycles. Both full-term and preterm babies with poor sleep organization are likely to be behaviorally disorganized and, therefore, to have difficulty learning and eliciting interactions from caregivers that enhance their development. In follow-ups during the preschool years, they show delayed motor, cognitive, and language development (Feldman, 2006; Holditch-Davis, Belyea, & Edwards, 2005; Weisman et al., 2011). And the brain-functioning problems that underlie newborn sleep irregularities may culminate in sudden infant death syndrome, a major cause of infant mortality (see the Social Issues: Health box on page 138).


Crying is the first way that babies communicate, letting parents know that they need food, comfort, or stimulation. During the weeks after birth, all babies seem to have some fussy periods when they are difficult to console. But most of the time, the nature of the cry, combined with the experiences that led up to it, help guide parents toward its cause. The baby’s cry is a complex stimulus that varies in intensity from a whimper to a message of all-out distress (Wood, 2009). As early as the first few weeks, infants can be identified by the unique vocal “signature” of their cries, which helps parents locate their baby from a distance (Gustafson, Green, & Cleland, 1994).

To soothe his crying infant, this father lifts her to his shoulder, holds her against his gently moving body, and speaks softly to her. This combination of physical contact, upright posture, motion, and gentle sounds causes infants to stop crying and become quietly alert.


Young infants usually cry because of physical needs, most commonly hunger, but may also cry in response to a change in temperature when undressed, a sudden noise, or a painful stimulus. Newborns (as well as older infants up to age 6 months) often cry at the sound of another crying baby—a response that may reflect an inborn capacity to react to the suffering of others (Dondi, Simion, & Caltran, 1999; Geangu et al., 2010). Furthermore, crying typically increases during the early weeks, peaks at about 4 to 6 weeks, and then declines (Barr, 2001). Because this trend appears in many cultures with vastly different infant care practices, researchers believe that normal readjustments of the central nervous system underlie it.

Social Issues: HealthThe Mysterious Tragedy of Sudden Infant Death Syndrome

Millie awoke with a start one morning and looked at the clock. It was 7:30, and 3-month-old Sasha had missed both her night waking and her early morning feeding. Wondering if she was all right, Millie tiptoed into Sasha’s room. She lay still under her blanket. Sasha had died silently during her sleep.

Sasha was a victim of sudden infant death syndrome (SIDS), the unexpected death, usually during the night, of an infant younger than 1 year of age that remains unexplained after thorough investigation. In industrialized nations, SIDS is the leading cause of infant mortality between 1 and 12 months, accounting for about 20 percent of these deaths in the United States (Centers for Disease Control and Prevention, 2018e).

SIDS victims usually show physical problems from the beginning. Early medical records of SIDS babies reveal higher rates of prematurity and low birth weight, poor Apgar scores, and limp muscle tone. Abnormal heart rate and respiration and disturbances in sleep–wake activity and in REM–NREM cycles while asleep are also involved (Cornwell & Feigenbaum, 2006; Garcia, Koschnitzky, & Ramirez, 2013). At the time of death, many SIDS babies have a mild respiratory infection (Blood-Siegfried, 2009). This seems to increase the chances of respiratory failure in an already vulnerable baby.

Mounting evidence indicates that impaired brain functioning is a major contributor to SIDS. Between 2 and 4 months, when SIDS is most likely to occur, reflexes decline and are replaced by voluntary, learned responses. Neurological weaknesses may prevent SIDS babies from acquiring voluntary behaviors that replace defensive reflexes (Horne, 2017; Rubens & Sarnat, 2013). As a result, when breathing difficulties occur during sleep, these infants do not wake up, shift their position, or cry out for help. Instead, they simply give in to oxygen deprivation and death. In support of this interpretation, autopsies reveal that the brains of SIDS victims contain unusually low levels of serotonin (a brain chemical that assists with arousal when survival is threatened) as well as other abnormalities in centers that control breathing and arousal (Salomonis, 2014).

Several environmental factors are linked to SIDS. Maternal cigarette smoking, both during and after pregnancy, as well as smoking by other caregivers, doubles risk of the disorder. Infants exposed to cigarette smoke arouse less easily from sleep and have more respiratory infections (Blackwell et al., 2015). Prenatal abuse of drugs that depress central nervous system functioning (alcohol, opiates, and barbiturates) increases the risk of SIDS as much as fifteen-fold (Hunt & Hauck, 2006; Maguire et al., 2016).

SIDS babies are also more likely to sleep on their stomachs than on their backs and often are wrapped very warmly in clothing and blankets. Infants who sleep on their stomachs less often wake when their breathing is disturbed, especially if they suffer from biological vulnerabilities (Richardson, Walker, & Horne, 2008). In other cases, healthy babies sleeping face down in soft bedding may suffocate from continually breathing their own exhaled breath, resulting in accidental deaths that would be incorrectly classified as SIDS.

SIDS rates are especially high among poverty-stricken ethnic minorities (Centers for Disease Control and Prevention, 2018e). In these families, parental stress, substance abuse, reduced access to health care, and lack of knowledge about safe sleep practices are widespread.

Dissemination of information to parents encouraging them to put their infants down on their backs to sleep has helped reduce the incidence of SIDS by more than half.

© BFG Images/Getty Images

The U.S. government’s Safe to Sleep campaign encourages parents to create safe sleep environments and engage in other protective practices (National Institutes of Health, 2018a). Recommendations include quitting smoking and drug taking, placing infants on their backs in light sleep clothing, providing a firm sleep surface, and eliminating soft bedding. An estimated 20 percent of SIDS cases would be prevented if all infants had smoke-free homes. Dissemination of information to parents about putting infants down on their backs has cut the incidence of SIDS by more than half (Behm et al., 2012). Other protective measures are breastfeeding, perhaps because it offers protection against respiratory infections (see Chapter 5), and pacifier use at bedtime: Sleeping babies who suck arouse more easily in response to breathing and heart-rate irregularities (Alm et al., 2016).

When SIDS does occur, surviving family members require a great deal of help to overcome a sudden and unexpected death. As Millie commented six months after Sasha’s death, “It’s the worst crisis we’ve ever been through. What’s helped us most are the comforting words of others who’ve experienced the same tragedy.”

The next time you hear a baby cry, notice your own reaction. The sound stimulates a sharp rise in alertness, the stress hormone cortisol, and feelings of arousal and discomfort in men and women, parents and nonparents alike (de Cock et al., 2015; Yong & Ruffman, 2014). This powerful response is probably innately programmed to help ensure that babies receive the care and protection they need to survive.

Applying What We Know

Soothing a Crying Baby



Talk softly or play rhythmic sounds.

Continuous, monotonous, rhythmic sounds (such as a clock ticking, a fan whirring, or peaceful music) are more effective than intermittent sounds.

Offer a pacifier.

Sucking helps babies control their own level of arousal.

Massage the baby’s body.

Stroking the baby’s torso and limbs with continuous, gentle motions relaxes the baby’s muscles.

Swaddle the baby.

Restricting movement and increasing warmth often soothe a young infant.

Lift the baby to the shoulder and rock or walk.

This combination of physical contact, upright posture, and motion is an effective soothing technique, causing young infants to become quietly alert.

Take the baby for a short car ride or a walk in a baby carriage; swing the baby in a cradle.

Gentle, rhythmic motion of any kind helps lull the baby to sleep.

Combine several of the methods just listed.

Stimulating several of the baby’s senses at once is often more effective than stimulating only one.

If these methods do not work, let the baby cry for a short period.

Occasionally, a baby responds well to just being put down and will, after a few minutes, fall asleep.

Sources: Dayton et al., 2015; Evanoo, 2007; St James-Roberts, 2012.

Soothing Crying Infants

Although parents do not always interpret their baby’s cry correctly, their accuracy improves with experience. At the same time, they vary widely in responsiveness. Parents who are high in empathy (ability to take the perspective of others in distress) and who hold “child-centered” attitudes toward infant care (for example, believe that babies cannot be spoiled by being picked up) are more likely to respond quickly and sensitively (Cohen-Bendahan, van Doornan, & deWeerth, 2014; Leerkes, 2010).

Fortunately, there are many ways to soothe a crying baby when feeding and diaper changing do not work (see Applying What We Know above). The technique that Western parents usually try first, lifting the baby to the shoulder and rocking or walking, is highly effective. Another common soothing method is swaddling—wrapping the baby snugly in a blanket. The Quechua people of the cold, high-altitude desert regions of Peru dress young infants in several layers of clothing and blankets that cover the head and body, a technique that reduces crying and promotes sleep (Tronick, Thomas, & Daltabuit, 1994). It also allows babies to conserve energy for early growth in their harsh environment.

In many tribal and village societies and in non-Western developed nations (such as Japan and Vietnam), young infants are in physical contact with their caregivers nearly continuously. Infants in these cultures show shorter bouts of crying than their American counterparts (Barr, 2001; Murray et al., 2018). When Western parents choose to practice proximal parenting by holding their babies extensively and responding swiftly to their cries, the amount of crying in the early months is reduced by about one-third (St James-Roberts, 2012).

The Bedouin people of the Middle East tightly swaddle young infants, a practice that reduces crying and promotes sleep.

© robertharding/Alamy Stock Photo

Abnormal Crying

Like reflexes and sleep patterns, the infant’s cry offers a clue to central nervous system distress. The cries of brain-damaged babies and those who have experienced prenatal and birth complications are often shrill, piercing, and shorter in duration than the cries of healthy infants (Green, Irwin, & Gustafson, 2000). Even newborns with a fairly common problem—colic, or bouts of persistent, hard-to-soothe crying—tend to have high-pitched, harsh-sounding cries. Although the cause of colic is unknown, certain newborns, who react especially strongly to unpleasant stimuli, are susceptible. Because their crying is intense, they find it harder to calm down than other babies (St James-Roberts, 2007). Colic generally subsides between 3 and 6 months.

Most parents try to respond to a crying baby’s call for help with extra care and attention, but sometimes the cry is so unpleasant and the infant so difficult to soothe that parents become exhausted, resentful, and angry. Preterm and ill babies are more likely to be abused by highly stressed parents, who sometimes mention a high-pitched, grating cry as one factor that caused them to lose control (Barr et al., 2014; de Weerth & St James-Roberts, 2017). (We will discuss a host of additional influences on child abuse in Chapter 10.)

Look and Listen

In a public setting, watch several parents soothe their crying babies. What techniques did the parents use, and how successful were they?

In a study of a large, nationally representative sample of Dutch infants, excessive crying in the early weeks elevated the risk of child behavior problems at age 5 to 6 years, especially when mothers viewed infant care as burdensome and the crying led them to speak angrily to or slap their baby (Smarius et al., 2017). Support programs for parents can help prevent these negative outcomes. In one intervention, nurses made periodic home visits during which they taught parents to identify early warning signs that their colicky baby was becoming overly aroused, to use effective soothing techniques, and to modify light, noise, and activity in the home to promote predictable sleep–wake cycles (Keefe et al., 2005). Colicky infants in the intervention group spent far less time crying than no-intervention controls—1.3 versus 3 hours per day.

4.5.3 Sensory Capacities

On his visit to class, Joshua looked wide-eyed at Yolanda’s bright pink blouse and readily turned to the sound of her voice. During feedings, he lets Yolanda know by the way he sucks that he prefers the taste of breast milk to a bottle of plain water. Clearly, Joshua has some well-developed sensory capacities. In the following sections, we explore the newborn baby’s responsiveness to touch, taste, smell, sound, and visual stimulation.


In our discussion of preterm infants, we saw that touch helps stimulate early physical growth. And as we will see in Chapter 7, it is vital for emotional development as well. Therefore, it is not surprising that sensitivity to touch is well-developed at birth.

The reflexes listed in Table 4.2 on page 134 in section 4.6.1 reveal that the newborn baby responds to touch, especially around the mouth, on the palms, and on the soles of the feet. During the prenatal period, these areas, along with the genitals, are the first to become sensitive to touch (Humphrey, 1978; Streri, 2005). Newborns, even those born several weeks preterm, use touch to investigate their world. When small objects are placed in their palms, they can distinguish shape (prism versus cylinder) and texture (smooth versus rough), as indicated by their tendency to hold on longer to an object with an unfamiliar shape or texture than to a familiar object (Lejeune et al., 2012; Molina et al., 2015; Sann & Streri, 2007, 2008).

At birth, infants are highly sensitive to pain. If male newborns are circumcised, anesthetic is sometimes not used because of the risk of giving drugs to a very young infant. Babies often respond with a high-pitched, stressful cry and a dramatic rise in heart rate, blood pressure, palm sweating, pupil dilation, and muscle tension (Lehr et al., 2007; Warnock & Sandrin, 2004). Brain-imaging research suggests that because of central nervous system immaturity, preterm and male babies feel the pain of a medical injection especially intensely (Bartocci et al., 2006).

Certain local analgesics for newborns ease the pain of these procedures. As a supplement to pain-relieving medication, offering a nipple that delivers a sugar solution is helpful; it quickly reduces crying and discomfort in young infants, preterm and full-term alike (Roman-Rodriguez et al., 2014). Breast milk is especially effective: Even the smell of the milk of the baby’s mother reduces infant stress to a routine blood-test heel stick more readily than the odor of another mother’s milk or of formula (Badiee, Asghari, & Mohammadizadeh, 2013; Nishitani et al., 2009). Combining breastfeeding with maternal gentle holding lessens pain even more (Axelin, Salantera, & Lehtonen, 2006; Obeidat & Shuriquie, 2015). Both sweet liquid and physical touch release endorphins—painkilling chemicals in the brain.

Allowing a baby to endure severe pain overwhelms the nervous system with stress hormones, which can disrupt the child’s developing capacity to handle common, everyday stressors (Walker, 2013). The result is heightened pain sensitivity, sleep disturbances, feeding problems, and difficulty calming down when upset.

Taste and Smell

Facial expressions reveal that newborns can distinguish several basic tastes. Like adults, they relax their facial muscles in response to sweetness, purse their lips when the taste is sour, and show a distinct archlike mouth opening when it is bitter. Similarly, certain odor preferences are present at birth. For example, the smell of bananas or chocolate causes a pleasant facial expression, whereas the odor of rotten eggs makes the infant frown (Steiner, 1979; Steiner et al., 2001). These reactions are important for survival: The food that best supports the infant’s early growth is the sweet-tasting milk of the mother’s breast. Not until 4 months do babies prefer a salty taste to plain water, a change that may prepare them to accept solid foods (Mennella & Beauchamp, 1998).

During pregnancy, the amniotic fluid is rich in tastes and smells that vary with the mother’s diet—early experiences that influence newborns’ preferences. In a study carried out in the Alsatian region of France, where anise is frequently used to flavor foods, researchers tested newborns for their reaction to the anise odor (Schaal, Marlier, & Soussignan, 2000). The mothers of some babies had regularly consumed anise during the last two weeks of pregnancy; the other mothers had never consumed it. When presented with the anise odor on the day of birth, the babies of anise-consuming mothers more often displayed facial expressions of interest and liking. In contrast, those of non-anise-consuming mothers were far more likely to turn away with negative facial expressions (see Figure 4.7). These different reactions were still apparent four days later, even though all mothers had refrained from consuming anise during this time.

In some instances, exposure to a flavor, either prenatally in the amniotic fluid or during the weeks after birth in breast milk, can have long-term consequences for odor and taste preferences. Compared to newborns of mothers who rarely drank alcohol during pregnancy, newborns whose mothers had frequently consumed alcoholic drinks more often displayed positive facial expressions to the odor of alcohol in the first two weeks of life—mouthing, sucking, smiling, and sticking out their tongues (Faas et al., 2015). This prenatally influenced attraction to alcohol is still evident in adolescence and early adulthood, even after other factors known to affect alcohol intake are controlled, such as genetic predisposition assessed through family history of alcoholism (Alati et al., 2006; Baer et al., 2003).

Figure 4.7 Examples of facial expressions of newborns exposed to the odor of anise whose mothers’ diets differed in anise-flavored foods during late pregnancy. (a) Babies of anise-consuming mothers spent more time turning toward the odor and sucking, licking, and chewing. (b) Babies of non-anise-consuming mothers more often turned away with a negative facial expression. (From B. Schaal, L. Marlier, & R. Soussignan, 2000, “Human Foetuses Learn Odours from Their Pregnant Mother’s Diet,” Chemical Senses, 25, p. 731. Reprinted by permission of Oxford University Press and Benoist Schaal.)

At the same time, young infants can learn to prefer a taste that at first evoked either a negative or neutral response. Bottle-fed newborns allergic to cow’s milk formula who are given a soy or other vegetable-based substitute (typically very sour and bitter-tasting) soon prefer it to regular formula. When first given solid foods several months later, these infants display an unusual liking for bitter-tasting cereals (Beauchamp & Mennella, 2011). This taste preference is still present at age 4 to 5 years, in more positive responses to foods with sour and bitter tastes than shown by their agemates.

In mammals, including humans, the sense of smell—in addition to playing an important role in feeding—helps mothers and babies identify each other. At 2 to 4 days of age, breastfed babies prefer the odor of their own mother’s breast and underarm to that of an unfamiliar lactating woman (Cernoch & Porter, 1985; Marin, Rapisardi, & Tani, 2015). And both breast- and bottle-fed 3- to 4-day-olds orient more to the smell of unfamiliar human milk than to formula milk, indicating that (even without postnatal exposure) the odor of human milk is more attractive to newborns (Marlier & Schaal, 2005). Newborns’ dual attraction to the odors of their mother and of breast milk helps them locate an appropriate food source and, in the process, begin to distinguish their caregiver from other people.


Although conduction of sound through the structures of the ear and transmission of auditory information to the brain are inefficient at birth, newborn infants can hear a wide variety of sounds—sensitivity that improves greatly over the first few months (Johnson & Hannon, 2015). At birth, infants prefer complex sounds, such as noises and voices, to pure tones. And babies only a few days old can tell the difference between a variety of sound patterns: a series of tones arranged in ascending versus descending order; tone sequences with a rhythmic downbeat (as in music) versus those without; utterances with two versus three syllables; the stress patterns of words, such as “ma-ma” versus “ma-ma”; happy-sounding speech as opposed to speech with negative or neutral emotional qualities; and even two languages spoken by the same bilingual speaker, as long as those languages differ in their rhythmic features—for example, French versus Russian (Mastropieri & Turkewitz, 1999; Ramus, 2002; Sansavini, Bertoncini, & Giovanelli, 1997; Trehub, 2001; Winkler et al., 2009).

Young infants listen longer to human speech than to structurally similar nonspeech sounds (Vouloumanos, 2010). And they can detect the sounds of any human language. Newborns make fine-grained distinctions among many speech sounds. For example, when given a nipple that turns on a recording of the “ba” sound, babies suck vigorously for a while and then slow down as the novelty wears off. When the sound switches to “ga,” sucking picks up, indicating that infants detect this subtle difference. Using this method, researchers have found only a few speech sounds that newborns cannot discriminate. Their ability to perceive sounds not found in their own language is more precise than an adult’s (Jusczyk & Luce, 2002). These capacities, which build on the fetus’s sensitivity to human speech in the weeks before birth (see page 96 in Chapter 3), reveal that the baby is marvelously prepared for the awesome task of acquiring language.

Responsiveness to sound also supports the newborn baby’s exploration of the environment. Infants as young as 3 days turn their eyes and head in the general direction of a sound. The ability to identify the precise location of a sound improves greatly over the first six months and shows further gains through the preschool years (Litovsky & Ashmead, 1997).

Listen carefully to yourself the next time you talk to a young baby. You will probably speak in ways that highlight important parts of the speech stream—using a slow, high-pitched, expressive voice with a rising tone at the ends of phrases and sentences and pausing before continuing. Adults probably communicate this way with infants because they notice that babies are more attentive when they do so. Indeed, newborns prefer speech with these characteristics: On hearing it, they focus more intently on the speaker’s face (Guellaï et al., 2016; Saffran, Werker, & Werner, 2006). They will also suck more on a nipple to hear a recording of their own mother’s voice than that of an unfamiliar woman and to hear their native language as opposed to a foreign language (Moon, Cooper, & Fifer, 1993; Spence & DeCasper, 1987). These preferences probably developed from hearing the muffled sounds of the mother’s voice before birth.

A newborn baby, primed and ready for the awesome task of acquiring language, gazes intently at his mother, listening attentively as she talks to him.



Vision is the least-developed of the newborn baby’s senses. Visual structures in both the eye and the brain are not yet fully formed at birth. For example, cells in the retina, the membrane lining the inside of the eye that captures light and transforms it into messages that are sent to the brain, are not as mature or densely packed as they will be in several months. The optic nerve that relays these messages, and visual centers in the brain that receive them, will not be adultlike for several years. And muscles of the lens, which permit us to adjust our visual focus to varying distances, are weak (Johnson & Hannon, 2015).

As a result, newborns cannot focus their eyes well, and their visual acuity, or fineness of discrimination, is limited. At birth, infants perceive objects at a distance of 20 feet about as clearly as adults do at 600 feet (Slater et al., 2010). In addition, unlike adults (who see nearby objects most clearly), newborn babies see unclearly across a wide range of distances (Banks, 1980; Hainline, 1998). As a result, images such as the parent’s face, even from close up, look like the blurry image in Figure 4.8. Nevertheless, as we will see in Chapter 5, newborns can detect human faces. And as with their preference for their mother’s smell and voice, from repeated exposures they quickly learn to prefer her face to that of an unfamiliar woman, although they are more sensitive to its broad outlines than its fine-grained, internal features (Bartrip, Morton, & de Schonen, 2001; Walton, Armstrong, & Bower, 1998).

Figure 4.8 View of the human face by the newborn and the adult. The newborn baby’s limited focusing ability and poor visual acuity lead the mother’s face, even when viewed from close up, to look much like the fuzzy image in (a) rather than the clear image in (b). Also, newborn infants have some color vision, although they have difficulty discriminating colors. Researchers speculate that colors probably appear similar, but less intense, to newborns than to older infants and adults. (From Kellman & Arterberry, 2006; Slater et al., 2010.)

Although they cannot yet see well, newborns actively explore their environment by scanning it for interesting sights and tracking moving objects. However, their eye movements are slow and inaccurate (von Hofsten & Rosander, 1998). Joshua’s captivation with my pink blouse reveals that he is attracted to bright objects. Nevertheless, once newborns focus on an object, they tend to look only at a single feature—for example, the corner of a triangle instead of the entire shape. And despite their preference for colored over gray stimuli, newborn babies are not yet good at discriminating colors. It will take about four months for color vision to become adultlike (Johnson & Hannon, 2015).

4.5.4 Neonatal Behavioral Assessment

A variety of instruments permit doctors, nurses, and researchers to assess the behavior of newborn babies. The most widely used of these tests, T. Berry Brazelton’s Neonatal Behavioral Assessment Scale (NBAS), evaluates the newborn’s reflexes, muscle tone, state changes, responsiveness to physical and social stimuli, and other reactions (Brazelton & Nugent, 2011). An instrument consisting of similar items, the Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS), is specially designed for use with newborns at risk for developmental problems because of low birth weight, preterm delivery, prenatal substance exposure, or other conditions (Tronick & Lester, 2013). Scores are used to recommend appropriate interventions and to guide parents in meeting their baby’s unique needs.

The NBAS has been given to many infants around the world, enabling researchers to learn about individual and cultural differences in newborn behavior. For example, compared with scores of European-American infants, NBAS scores of Asian- and Native-American babies reveal less irritability. Mothers in these cultures often encourage their babies’ calm dispositions through holding and nursing at the first signs of discomfort (Muret-Wagstaff & Moore, 1989; Small, 1998). The Kipsigis of Kenya, who highly value infant motor maturity, massage babies regularly and begin exercising the stepping reflex shortly after birth. These customs contribute to Kipsigis babies’ strong but flexible muscle tone at 5 days of age (Super & Harkness, 2009). Newborns whose mothers experienced depression during pregnancy score considerably lower than those of nondepressed mothers in neurobehavioral maturity (Figueiredo et al., 2017). But with warm, attentive caregiving, NBAS scores can readily improve. In Zambia, Africa, close mother–infant contact throughout the day quickly changed the poor NBAS scores of undernourished newborns (Brazelton, Koslowski, & Tronick, 1976). At age 1 week, these unresponsive infants appeared alert, responsive, and content.

A Senegalese mother carries her baby in a sling throughout the day, a practice that maintains close physical contact, enables nursing at the first signs of discomfort, and promotes a calm, contented state.

Inger Vandyke / VWPics / Alamy Stock Photo

Because newborn behavior and parenting combine to influence development, changes in scores over the first week or two of life (rather than a single score) provide the best estimate of the baby’s ability to recover from the stress of birth. NBAS “recovery curves” predict intelligence and absence of emotional and behavior problems with moderate success well into the preschool years (Brazelton, Nugent, & Lester, 1987; Ohgi et al., 2003a, 2003b).

In some hospitals, health professionals use the NBAS or the NNNS to help parents get to know their newborns through discussion or demonstration of the capacities these instruments assess. Parents who participate in these programs, compared with no-intervention controls, interact more confidently and effectively with their babies (Browne & Talmi, 2005; Bruschweiler-Stern, 2004). Although lasting effects on development have not been demonstrated, NBAS-based interventions are useful in helping the parent–infant relationship get off to a good start.

Ask Yourself

Connect ■ How do the diverse capacities of newborn babies contribute to their first social relationships? Provide as many examples as you can.

Apply ■ After a difficult delivery, Jackie observes her 2-day-old daughter, Kelly, being given the NBAS. Kelly scores poorly on many items. Seeing this, Jackie wonders if Kelly will develop normally. How would you respond to Jackie’s concern?

Reflect ■ Are newborns more competent than you thought they were before you read this chapter? Which of their capacities most surprised you?


4.6a Discuss the influence of birth-related hormonal changes and parent–infant contact on emergence of parental affection and concern for the newborn.

4.6b Describe changes in the family after the birth of a baby, along with interventions that foster the transition to parenthood.

Yolanda and Jay’s account of Joshua’s birth in the opening to this chapter revealed that holding and touching him after delivery was an experience filled with intense emotion. Most parents are overjoyed at their baby’s arrival, describe the experience as “awesome,” “indescribable,” or “unforgettable,” and display intense interest in their newborn child—stroking the baby gently, looking into the infant’s eyes, and speaking softly.

As we will see, effective caregiving is so crucial for infant survival and optimal development that nature helps prepare mothers and fathers for their new role. Yet biological changes are but one dimension of this transformative time of life. The transition to parenthood is a complex, often stressful process involving profound alterations in family roles, relationships, and responsibilities. Parents who find productive ways of overcoming difficulties adjust well, with great benefits for the parent–infant relationship.

4.6.1 Early Parent–Infant Contact

Toward the end of pregnancy, mothers begin producing higher levels of the hormone oxytocin, which causes the breasts to “let down” milk; induces a calm, relaxed mood; and heightens responsiveness to the newborn (Gordon et al., 2010; Gregory et al., 2015). Fathers, too, show hormonal changes around the time of birth that are compatible with those of mothers—specifically, slight increases in prolactin (a hormone that stimulates milk production in females), estrogens (sex hormones produced in larger quantities in females), and oxytocin, and a decrease in androgens (sex hormones produced in larger quantities in males) (Storey & Zigler, 2016). These changes, which are induced by a warm couple relationship and fathers’ contact with mother and baby, predict paternal involvement and sensitive interactions with infants (Abraham et al., 2014; Edelstein et al., 2017; Feldman, 2014).

Do human parents require close physical contact in the hours after birth for bonding, or affection and concern for the infant, to emerge—as many animal species do? Current evidence shows that the human parent–infant relationship does not depend on a precise, early period of togetherness. Some parents report sudden, deep feelings of affection on first holding their babies. For others, these emotions emerge gradually. And as successful adoption reveals (see page 64 in Chapter 2), humans can parent effectively without experiencing birth-related hormonal changes. In fact, when foster and adoptive mothers hold and interact with their nonbiological infants, they typically release oxytocin (Bick et al., 2013; Galbally et al., 2011). The greater their oxytocin production, the more they express affection and pleasure toward the infant.

Human bonding depends on many factors, not just on what happens during a short period after birth. Nevertheless, early contact with the baby may be one of several factors that help build a good parent–infant relationship. Realizing this, today hospitals offer rooming in, in which the infant stays in the mother’s hospital room all or most of the time. If parents do not choose this option or cannot do so for medical reasons, there is no evidence that their competence as caregivers will be compromised or that the baby will suffer emotionally.

A father radiates intense emotion as he gently cradles and kisses his newborn baby. Fathers, like mothers, experience hormonal changes around the time of birth that can heighten involvement and sensitive interactions with the infant.


4.6.2 Changes in the Family System

The early weeks after a baby enters the family are a taxing time for new parents. The mother needs to recover from childbirth. If she is breastfeeding, energies must be devoted to working out this intimate relationship. The other parent must become part of what is now a threesome while supporting the mother in her recovery. While all this is going on, the tiny infant is assertive about urgent physical needs, demanding to be fed, changed, and comforted at odd times of the day and night. The family schedule becomes irregular and uncertain, and parental sleep deprivation and consequent daytime fatigue are often major challenges (Insana & Montgomery-Downs, 2012). Yolanda spoke candidly about the changes she and Jay experienced:

When we brought Joshua home, he seemed so small and helpless, and we worried about whether we would be able to take proper care of him. It took us 20 minutes to change the first diaper. I rarely feel rested because I’m up two to four times every night, and I spend a good part of my waking hours trying to anticipate Joshua’s rhythms and needs. If Jay weren’t so willing to help by holding and walking Joshua, I think I’d find it much harder.

The demands of new parenthood—constant caregiving, added financial responsibilities, and less time for couples to devote to one another—usually cause parents’ gender roles to become more traditional (Katz-Wise, Priess, & Hyde, 2010; Yavorsky, Dush, & Schoppe-Sullivan, 2015). This is true even for couples like Yolanda and Jay, who are strongly committed to gender equality and are used to sharing household tasks. Yolanda took a leave of absence from work, whereas Jay’s career continued as it had before. As a result, Yolanda spent more time at home with the baby, while Jay focused more on his provider role.

For most new parents, however, the arrival of a baby—though often followed by mild declines in relationship and overall life satisfaction—does not cause significant marital strain. Marriages that are gratifying and supportive tend to remain so (Doss et al., 2009; Luhmann et al., 2012). But troubled marriages usually become more distressed after a baby is born (Houts et al., 2008). And when mothers or fathers perceive their partner as unsupportive in parenting, they experience an especially difficult post-birth adjustment (Don & Mickelson, 2014; Driver et al., 2012). For some new parents, problems are severe (see the Biology and Environment box on page 146).

Violated expectations about division of labor after childbirth powerfully affect family well-being. In dual-earner marriages, the larger the difference between men’s and women’s responsibilities for caregiving and household chores, the more conflict-ridden their interaction becomes and the more their marital satisfaction suffers, especially for women—with negative consequences for parent–infant interaction (Chong & Mickelson, 2013; Moller, Hwang, & Wickberg, 2008). In contrast, sharing caregiving and other tasks predicts greater parental happiness and sensitivity to the baby. These findings highlight the vital importance of the coparenting relationship for new parents’ adjustment and children’s development.

Biology and EnvironmentParental Depression and Child Development

About 8 to 10 percent of women experience chronic depression—mild to severe feelings of sadness and withdrawal that continue for months or years. Often, the beginnings of this emotional state cannot be pinpointed. In other instances, depression emerges or strengthens after childbirth but fails to subside (Paulson & Bazemore, 2010). This is called postpartum depression.

Although it is less recognized and studied, fathers, too, experience chronic depression. About 5 percent of fathers report symptoms after the birth of a child (Cameron, Sedov, & Tomfohr-Madsen, 2016). Parental depression can interfere with effective parenting and seriously impair children’s development. As noted in Chapter 2, genetic makeup increases the risk of depressive illness, but social and cultural factors are also involved.

Maternal Depression

During Julia’s pregnancy, her husband, Kyle, showed so little interest in their anticipated baby that Julia worried that having a child might be a mistake. Shortly after Lucy was born, Julia’s mood plunged. She felt anxious and weepy, overwhelmed by Lucy’s needs, and angry at loss of control over her own schedule. When Julia approached Kyle about her own fatigue and his unwillingness to help with the baby, he snapped that she was overreacting.

Julia’s depressed mood quickly affected her baby. In the weeks after birth, infants of depressed mothers sleep poorly, are less attentive to their surroundings, and have elevated levels of the stress hormone cortisol (Fernandes et al., 2015; Goodman et al., 2011; Natsuaki et al., 2014). The more extreme the depression and the greater the number of stressors in a mother’s life (such as marital discord, little or no social support, and poverty), the more the parent–child relationship suffers. Julia rarely smiled at, comforted, or talked to Lucy, who responded to her mother’s sad, vacant gaze by turning away, crying, and often looking sad or angry herself (Field, 2011; Vaever et al., 2015). Julia, in turn, felt guilty and inadequate, and her depression deepened. By age 6 months, Lucy showed symptoms common in babies of depressed mothers—delays in motor and cognitive development, poor emotion regulation, an irritable mood, and attachment difficulties (Ibanez et al., 2015; Lefkovics, Baji, & Rigó, 2014; Vedova, 2014).

When maternal depression persists, the parent–child relationship worsens. Depressed parents view their infants negatively, which contributes to their inept caregiving (Lee & Hans, 2015). As their children get older, lack of warmth and involvement is often accompanied by inconsistent discipline—sometimes lax, at other times too forceful (Thomas et al., 2015). As we will see in later chapters, children who experience these maladaptive parenting practices often have serious adjustment problems. Some withdraw into a depressive mood themselves; others become impulsive and aggressive (Rotheram-Fuller et al., 2018).

Paternal Depression

Paternal depression is also linked to dissatisfaction with marriage after childbirth and to other life stressors, including job loss and divorce (Bielawska-Batorowicz & Kossakowska-Petrycka, 2006; Kerstis et al., 2016). In a study of a large representative sample of British parents and babies, researchers assessed depressive symptoms of fathers shortly after birth and again the following year. Then they tracked the children’s development into the preschool years (Ramchandani et al., 2008). Persistent paternal depression was, like maternal depression, a strong predictor of child behavior problems—especially overactivity, defiance, and aggression in boys.

Paternal depression is linked to frequent father–child conflict as children grow older (Gutierrez-Galve et al., 2015). Over time, children subjected to parental negativity develop a pessimistic worldview—one in which they lack self-confidence and perceive their parents and other people as threatening. Children who constantly feel in danger are especially likely to become overly aroused in stressful situations, easily losing control in the face of cognitive and social challenges (Sturge-Apple et al., 2008). Although children of depressed parents may inherit a tendency toward emotional and behavior problems, quality of parenting is a major factor in their adjustment.

A mother discusses her postpartum depression with her doctor. Early treatment is vital for preventing parental depression from interfering with the parent–child relationship.



Early treatment is vital to prevent parental depression from interfering with the parent–child relationship. Julia’s doctor referred her to a therapist, who helped Julia and Kyle with their marital problems. At times, antidepressant medication is prescribed.

In addition to alleviating parental depression, therapy that encourages depressed parents to revise their negative views of their babies and to engage in emotionally positive, responsive caregiving is vital for reducing developmental problems (Goodman et al., 2015). When a depressed parent does not respond easily to treatment, a warm relationship with the other parent or another caregiver can safeguard children’s development.

Applying What We Know

How Couples Can Ease the Transition to Parenthood



Devise a plan for sharing household tasks.

As soon as possible, discuss division of household responsibilities. Decide who does a particular chore based on who has the needed skill and time, not gender. Schedule regular times to reevaluate your plan to fit changing family circumstances.

Begin sharing child care right after the baby’s arrival.

For fathers, strive to spend equal time with the baby early. For mothers, refrain from imposing your standards on your partner. Instead, share the role of “child-rearing expert” by discussing parenting values and concerns often. Attend a new-parenthood course together.

Talk over conflicts about decision making and responsibilities.

Face conflict through communication. Clarify your feelings and needs, and express them to your partner. Listen and try to understand your partner’s point of view. Then be willing to negotiate and compromise.

Establish a balance between work and parenting.

Critically evaluate the time you devote to work in view of new parenthood. If it is too much, try to cut back.

Press for workplace and public policies that assist parents in rearing children.

Difficulties faced by new parents may be partly due to lack of workplace and societal supports. Encourage your employer to provide benefits that help combine work and family roles, such as paid employment leave, flexible work hours, and on-site, high-quality, affordable child care. Communicate with lawmakers about improving policies for children and families, including paid, job-protected leave to support the transition to parenthood.

Postponing parenthood until the late twenties or thirties, as many couples do today, eases the transition to parenthood. Waiting permits couples to pursue occupational goals, gain life experience, and strengthen their relationship. Under these circumstances, men are more enthusiastic about becoming fathers and therefore more willing to participate. And women whose careers are well under way and whose marriages are happy are more likely to encourage their husbands to share housework and child care, which fosters fathers’ involvement (Lee & Doherty, 2007; Schoppe-Sullivan et al., 2008).

A second birth typically requires that fathers take an even more active role in parenting—by caring for the firstborn while the mother is recuperating and by sharing in the high demands of tending to both a baby and a young child. Consequently, well-functioning families with a newborn second child typically pull back from the traditional division of responsibilities that occurred after the first birth. In one study, fathers in dual earner families who believed strongly in gender equality tended to be more involved with their first-borns after the second child’s arrival, particularly when the births of their two children were closely spaced (Kuo, Volling & Gonzalez, 2018). As we will see in Chapter 7, first-born children—especially those who are toddlers or young preschoolers at the time of the second birth—understandably may feel displaced and react with jealousy and anger. For strategies couples can use to ease the transition to parenthood, refer to Applying What We Know above.

The arrival of a baby profoundly changes family functioning. For couples in gratifying and supportive marriages with a positive coparenting relationship in which caregiving and household chores are shared, the stress of parenthood typically remains manageable, contributing to favorable child development.


4.6.3 Single-Mother Families

About 40 percent of U.S. births are to single mothers, one-third of whom are teenagers (Martin et al., 2018). Although the U.S. adolescent birth rate has undergone a steady decline, it remains high compared with that of other developed nations.

At the other extreme, planned births and adoptions by never-married single 30- to 45-year-old women with at least a bachelor’s degree have doubled compared with two decades ago. Nearly one-third have at least one child (Pew Research Center, 2018e). These mothers are generally financially secure, have readily available social support from family members and friends, and adapt to parenthood with relative ease. In fact, older single mothers in well-paid occupations who plan carefully for a new baby may encounter fewer parenting difficulties than married couples, largely because their family structure is simpler: They do not have to coordinate parenting roles with a partner, and they have no unfulfilled expectations for shared caregiving (Tyano et al., 2010). Also, because of their psychological maturity, these mothers are likely to cope effectively with parenting challenges.

Look and Listen

Ask a couple or a single mother to describe the challenges of new parenthood, along with factors that aided or impeded this transition.

The majority of nonmarital births are unplanned and to women in their twenties. Most have incomes below the poverty level and experience a stressful transition to parenthood. Although many live with the baby’s father or another partner, cohabiting relationships in the United States, compared with those in Western Europe, involve less commitment and cooperation and are far more likely to break up—especially after an unplanned baby arrives (Guzzo, 2014; Jose, O’Leary, & Moyer, 2010). These single mothers often lack emotional and parenting support—strong predictors of psychological distress and infant caregiving difficulties (Keating-Lefler et al., 2004).

4.6.4 Parent Interventions

Special interventions are available to help parents adjust to life with a new baby. For those who are not at high risk for problems, counselor-led programs that focus on strengthening the couple’s relationship and their coparenting skills are particularly successful (Gottman, Gottman, & Shapiro, 2010; Schulz, Cowan, & Cowan, 2006).

In one evaluation of two brief interventions, first-time expectant couples received four 90-minute individualized coaching sessions—two shortly before birth and two 3 months after birth—aimed either at solving relationship challenges or at devising a coparenting plan for mutually supportive, shared caregiving. Compared to control-group women, those randomly assigned to either intervention reported large post-birth benefits in relationship satisfaction and in mutually supportive coparenting that were still evident two years after the birth (see Figure 4.9). Also, women experiencing the interventions were far less likely than controls to report a sharp rise in stress during their baby’s first year (Doss et al., 2014). Men also benefitted from the interventions, though not as much as women, perhaps because overall, men experience fewer difficulties during the transition to parenthood.

Figure 4.9 Impact of parent interventions focusing on the couple’s relationship and on supportive coparenting during the transition to parenthood. Ninety couples who were either married or cohabiting were randomly assigned to either a relationship-focused intervention, a coparenting-focused intervention, or a control group receiving written materials about infant care. As shown here, women receiving either intervention reported far more favorable coparenting throughout their baby’s first two years than did control-group women. Women’s relationship satisfaction with their partners showed similar post-birth trends. (From B. D. Doss et al., 2014, “A Randomized Controlled Trial of Brief Coparenting and Relationship Interventions During the Transition to Parenthood,” Journal of Family Psychology, p. 490. Copyright © 2014 American Psychological Association. Adapted by permission.)

High-risk parents struggling with poverty or the birth of a baby with disabilities need more intensive interventions. Programs in which a professional intervener visits the home and focuses on enhancing social support and parenting have resulted in improved parent–infant interaction and benefits for children’s cognitive and social development into middle childhood (to review one example, return to page 110 in Chapter 3). Many low-income single mothers benefit from interventions that focus on sustaining the father’s involvement (Jones, Charles, & Benson, 2013). These parents also require tangible support—money, food, transportation, and affordable child care—to ease stress so they have the psychological resources to engage in sensitive, responsive infant care.

When parents’ relationships are positive and cooperative, social support is available, and families have sufficient income, the stress caused by the birth of a baby remains manageable. These family conditions, as we have already seen, consistently contribute to favorable development—in infancy and beyond.

A counselor discusses options with this single mother for continuing her education. Parents struggling with poverty benefit from intensive intervention focusing on social support and effective parenting.


Ask Yourself

Connect ■ Explain how generous employment leave for childbirth—at least 12 weeks of paid time off available to either the mother or father—can ease the transition to parenthood and promote positive parent–infant interaction. (Hint: Consult the Cultural Influences box on pages 132–133 in section 4.4.2.)

Apply ■ Derek, father of a 3-year-old and a newborn, reported that he had a harder time adjusting to the birth of his second child than to that of his first. Explain why this might be so.

Reflect ■ If you are a parent, what was the transition to parenthood like for you? What factors helped you adjust? What factors made it more difficult? If you are not a parent, pose these questions to someone you know who recently became a parent.


4.1 The Stages of Childbirth (p. 117)

4.1 Describe the three stages of childbirth, the baby’s adaptation to labor and delivery, and the newborn baby’s appearance.

In the first stage, dilation and effacement of the cervix occur as uterine contractions increase in strength and frequency. This stage culminates in transition, a brief period of peak contractions in which the cervix opens completely. In the second stage, the mother feels an urge to push the baby through the birth canal, and the baby is born. In the final stage, the placenta is delivered.

During labor, infants produce high levels of stress hormones, which help them withstand oxygen deprivation, clear their lungs for breathing, and arouse them into alertness.

Newborns may be odd-looking, but their facial features make adults feel like cuddling them.

The Apgar Scale assesses the baby’s physical condition at birth.

4.2 Approaches to Childbirth (p. 121)

4.2 Describe natural childbirth and home delivery, noting benefits and concerns associated with each.

In natural, or prepared, childbirth, the expectant mother and a companion typically attend classes where they learn about labor and delivery, master relaxation and breathing techniques to counteract pain, and prepare for coaching during childbirth. Social support from a doula reduces the need for instrument-assisted births and pain medication and is associated with higher Apgar scores.

An upright position and water birth are increasingly popular alternatives that ease labor and delivery for both mother and baby, compared to the traditional lying on the back, feet in stirrups hospital position.

Home birth is safe for healthy mothers assisted by a well-trained doctor or midwife, but mothers at risk for any complication are safer giving birth in a hospital.

4.3 Medical Interventions (p. 123)

4.3 List common medical interventions during childbirth, circumstances that justify their use, and any dangers associated with each.

Fetal monitors help save the lives of many babies at risk for anoxia due to pregnancy complications. Used routinely, however, they may identify infants as in danger who are not, contributing to an increase in instrument and cesarean deliveries.

Use of analgesics and anesthetics to control pain, though sometimes necessary, can prolong labor and compromise newborn adjustment.

Although appropriate when the mother’s pushing is insufficient, instrument delivery can cause serious complications and should be avoided if possible.

Cesarean delivery is warranted for medical emergencies and in some cases of breech position. However, many unnecessary cesareans are performed.

4.4 Birth Complications (p. 126)

4.4a Describe risks associated with oxygen deprivation and with preterm and low-birth-weight infants, along with effective interventions.

Inadequate oxygen supply during labor and delivery can damage the brain, resulting in persisting motor and cognitive deficits that vary in severity with the extent of anoxia. Hypothermia treatment substantially reduces brain damage due to anoxia.

Low birth weight, most common in infants born to poverty-stricken women, is a major cause of neonatal and infant mortality and developmental problems.

Compared with preterm infants, whose weight is appropriate for time spent in the uterus, small-for-date infants usually have longer-lasting difficulties. However, even minimally preterm babies experience greater rates of illness and persisting, mild intellectual delays.

Some interventions for preterm infants provide special stimulation in the intensive care nursery. Others teach parents how to care for and interact with their babies. Preterm infants in stressed, low-income households need long-term, intensive intervention. Skin-to-skin “kangaroo care” promotes survival and diverse aspects of development in preterm infants.

Countries that outrank the United States in infant survival promote prenatal health and effective parenting through government-sponsored high-quality health care and generous, paid employment leave.

4.4b Describe factors that promote resilience in infants who survive a traumatic birth.

When infants experience birth trauma, a supportive family environment or relationships with other caring adults can help restore their growth. Even infants with fairly serious birth complications can recover with the help of positive life events.

4.5 The Newborn Baby’s Capacities (p. 133)

4.5a Describe the newborn baby’s reflexes and states of arousal, including sleep characteristics and ways to soothe a crying baby.

Reflexes are the newborn baby’s most obvious organized patterns of behavior. Some have survival value, others help parents and infants establish gratifying interaction, and still others provide the foundation for voluntary motor skills.

Although newborns move in and out of five states of arousal, they spend most of their time asleep. Sleep includes at least two states: rapid-eye-movement (REM) sleep and non-rapid-eye-movement (NREM) sleep. Newborns spend about 50 percent of their sleep time in REM sleep, far more than they ever will again. REM sleep provides young infants with stimulation essential for central nervous system development. Sleep contributes to babies’ learning and memory.

Disturbed REM–NREM cycles are a sign of central nervous system abnormalities, which may lead to sudden infant death syndrome (SIDS).

A crying baby triggers strong feelings of discomfort in nearby adults. Once feeding and diaper changing have been tried, lifting the baby to the shoulder and rocking or walking is a highly effective soothing technique. Extensive parent–infant physical contact substantially reduces crying in the early months. Support programs can help parents acquire techniques that reduce excessive infant crying.

4.5b Describe the newborn baby’s sensory capacities.

The senses of touch, taste, smell, and sound are well-developed at birth. Newborns use touch to investigate their world, are highly sensitive to pain, prefer sweet tastes and smells, and orient toward the odor of their own mother’s lactating breast and toward human milk rather than formula milk. Attraction to certain flavors, developed through prenatal exposure to a mother’s diet or through breast milk, can, in some instances have long-term consequences for odor and taste preferences.

Newborns can distinguish a variety of sound patterns as well as nearly all speech sounds. They are especially responsive to human speech, high-pitched expressive voices, their own mother’s voice, and speech in their native language.

Vision is the least developed of the newborn’s senses. At birth, focusing ability and visual acuity are limited. Nevertheless, newborns can detect human faces and prefer their mother’s familiar face to the face of a stranger. In exploring the visual field, they are attracted to bright objects but tend to limit their looking to single features. Newborn babies have difficulty discriminating colors.

4.5c Explain the usefulness of neonatal behavioral assessment.

The most widely used instrument for assessing the behavior of newborn infants, Brazelton’s Neonatal Behavioral Assessment Scale (NBAS), has helped researchers understand individual and cultural differences in newborn behavior.

Changes in NBAS scores over the first week or two of life provide the best estimate of the baby’s ability to recover from the stress of birth. Sometimes the NBAS is used to teach parents about their baby’s capacities.

4.6 The Transition to Parenthood (p. 144)

4.6a Discuss the influence of birth-related hormonal changes and parent–infant contact on emergence of parental affection and concern for the infant.

Near birth, mothers—as well as fathers in a warm couple relationship—experience hormonal changes associated with sensitivity and responsiveness to the baby. Although human parents do not require close physical contact with the infant immediately after birth for bonding to occur, hospital practices that promote parent–infant closeness, such as rooming in, may help parents build a good relationship with their newborn.

4.6b Describe changes in the family after the birth of a baby, along with interventions that foster the transition to parenthood.

In response to the demands of new parenthood, the gender roles of parents usually become more traditional. Parents in gratifying marriages who continue to support each other’s needs generally adapt well. But in dual-earner marriages, a large difference between a couple’s caregiving responsibilities can threaten marital satisfaction, especially for women, and negatively affect parent–infant interaction. Favorable adjustment to a second birth typically requires that fathers take an even more active role in parenting.

Early therapeutic intervention can prevent parental depression from interfering with effective caregiving and the parent–child relationship.

Planned births and adoptions by never-married, well-educated women in their thirties and forties have increased dramatically. These mothers typically adapt easily to parenthood. Most nonmarital births are unplanned and to poverty-stricken young women experiencing a stressful transition to parenthood.

When parents are at low risk for problems, counselor-led interventions that focus on strengthening the couple’s relationship and their coparenting skills can ease the transition to parenthood. High-risk parents struggling with poverty or the birth of a baby with disabilities are more likely to benefit from intensive home interventions focusing on enhancing social support and parenting.


anoxia (p. 123)

Apgar Scale (p. 120)

bonding (p. 145)

breech position (p. 125)

cesarean delivery (p. 125)

dilation and effacement of the cervix (p. 119)

fetal monitors (p. 123)

infant mortality (p. 132)

natural, or prepared, childbirth (p. 122)

Neonatal Behavioral Assessment Scale (NBAS) (p. 143)

neonatal mortality (p. 132)

non-rapid-eye-movement (NREM) sleep (p. 137)

preterm infants (p. 128)

rapid-eye-movement (REM) sleep (p. 137)

reflex (p. 133)

rooming in (p. 145)

small-for-date infants (p. 128)

states of arousal (p. 136)

sudden infant death syndrome (SIDS) (p. 138)

transition (p. 119)

visual acuity (p. 143)

Descriptions of Images and Figures

Back to Figure

The process is as follows.

• Stage 1. A, dilation and effacement of the cervix. Contractions of the uterus cause dilation and effacement of the cervix. B, transition. Transition is reached when the frequency and strength of the contractions are at their peak and the cervix opens completely.

• Stage 2. C, pushing. With each contraction, the mother pushes, forcing the baby down the birth canal, and the head appears. D, birth of the baby. Near the end of stage 2, the shoulders emerge, followed quickly by the rest of the baby’s body.

• Stage 3. E, delivery of the placenta. With a few final pushes, the placenta is delivered.

Back to Figure

The data is as follows, with the first number given as the percent discharged alive from hospital and the second the percent with a moderate to severe disability. 23 weeks: 30, 60. 24 weeks: 50, 40. 25 weeks: 60, 15. 26 weeks: 80, 10. 27 weeks: 90, 10. 28 weeks: 90, 10. All values are estimated.

Back to Figure

The graph shows the two groups, the maternal sounds group and the hospital noise group, and the mean standard score thickness of auditory areas for the left and right auditory cortex. The data is as follows.

• Maternal sounds group. Right: 4.1. Left: 7.8.

• Hospital noise group. Right: 2.9. Left: 6.1.

All values are estimated.

Back to Figure

The graph shows the mean change in verbal intelligence scores by the intensity of the intervention for 2 birth weight categories, light birth weight, which is less than 2,001 grams, and heavier birth weight, which is between 2,001 and 2,500 grams. The data is as follows.

• 100 to 300 days, low. Light: negative 2. Heavier: 4.5.

• Greater than 350 days, high. Light: 2, Heavier: 8.

• Greater than 400 days, very high. Light: 8. Heavier: 14.

All values are estimated.

Back to Figure

The number of deaths per 1,000 live births by nation are as follows.

• United States: 5.8

• Bosnia and Herzegovina: 5.3

• Latvia: 5.1

• Slovakia: 5

• Hungary: 4.8

• Canada: 4.5

• Greece: 4.5

• Cuba: 4.4

• New Zealand: 4.4

• Poland: 4.4

• Portugal: 4.3

• Australia: 4.2

• United Kingdom: 4.2

• Denmark: 3.9

• Slovenia: 3.9

• Estonia: 3.8

• Lithuania: 3.7

• Andorra: 3.6

• Ireland: 3.6

• Switzerland: 3.6

• Belarus: 3.6

• Malta: 3.5

• Netherlands: 3.5

• Israel: 3.4

• Austria: 3.3

• Luxembourg: 3.3

• Belgium: 3.3

• Germany: 3.3

• Spain: 3.2

• France: 3.1

• Italy: 3.1

• South Korea: 3

• Czech Republic: 2.7

• Sweden: 2.7

• Finland: 2.5

• Singapore: 2.5

• Norway: 2.5

• Iceland: 2.1

• Japan: 2

Back to Figure

The faces of the babies who are newborns of anise-consuming mothers show mild interest and yawning. The faces of the babies who are newborns of non-anise-consuming mothers show disgust and turning the face away.

Back to Figure

The graph shows the mean ratings by women of mutually supportive caregiving by the time since the baby’s birth in months. The curve labeled relationship-focused intervention rises slightly almost linearly from about 86.5 at 0 months to about 87.5 at 24 months. The curve labeled coparenting-focused intervention starts at about 88 at 0 months, curves up to almost 90 at 12 months, and the falls to about 87 at 24 months. The curve labeled control group starts at about 76 at 0 months and rises through about 78 at 12 months and 82 at 24 months. All values are estimated.




What is Theory?

Use this textbox to define theory in terms families could understand. If you use scholarly sources here, add them to the reference list on page 17.

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Two Developmental Theories

Use this textbox to explain two developmental theories that will drive your work with young children. If you use scholarly sources here, add them to the reference list on page 17.

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Use this textbox to discuss the connection between your chosen theories and using developmentally appropriate practice to support your work with young children. If you use scholarly sources here, add them to the reference list on page 17.

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Connection between theories & DAP

Page 2

Explain three resources for families to help them understand your chosen theories. Be sure to include a link to each resource.

Quick read resource for families on the go

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Detailed resource for families who want to learn more

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User-friendly resource for diverse families

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Page 3

Use this textbox to write your reflection. In your reflection, be sure to address the following:

Discuss why it is important for you to help families understand developmental theory.

Explain why it is important to research and theorize about childhood.

Describe how your stance on theory will evolve over the next five years.

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Two Genetic Factors

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Two Environmental Factors

Use this textbox to describe two environmental factors that can influence prenatal development. If you use scholarly sources here, add them to the reference list on page 17.

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Use this textbox to discuss how you will use Bronfenbrenner’s ecological systems theory to support families during the prenatal and newborn stage. If you use scholarly sources here, add them to the reference list on page 17.

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Bronfenbrenner’s Ecological Systems

Page 5

Explain three resources for families to support them during the prenatal and newborn stage of development. Be sure to include a link to each resource.

Quick read resource for families on the go

Use this textbox to provide one resource that would be a quick read for families on the go. (Explain why you chose this resource and provide a link.)

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

Detailed resource for families who want to learn more

Use this textbox to provide one resource that would be more detailed for families who want to learn more. (Explain why you chose this resource and provide a link.)

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

User-friendly resource for diverse families

Use this textbox to provide one resource that would be user-friendly for diverse families (e.g., ELL, single parents, grandparents raising grandchildren, etc.). (Explain why you chose this resource and provide a link.)

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

Page 6

Use this textbox to write your reflection. In your reflection, be sure to address the following:

Explain the role of an educator in supporting the prenatal development of families in their care.

Describe how the ideas you shared in the parent handout section of this assignment are supported by the theory you aligned with in your Week 1 Discussion: Child Development Theories.

Discuss how an understanding of each family’s cultural context can make you a more effective educator during this time frame.

If you use scholarly sources here, add them to the reference list on page 17.

**Delete all the text in this box before you begin your response.


Page 7

Cognitive and Language Development

Use this textbox to discuss how cognitive and language development are connected. If you use scholarly sources here, add them to the reference list on page 17.

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Motor and Social Development

Use this textbox to summarize how motor development influences infant and toddler social experiences. If you use scholarly sources here, add them to the reference list on page 17.

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Use this textbook to describe how you will create a learning environment that fosters the development of self-regulation, secure attachment, and self-control. If you use scholarly sources here, add them to the reference list on page 17.

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Learning Environment

Page 8

Explain three resources for families to support them during the infant and toddler stage of development. Be sure to include a link to each resource.

Quick read resource for families on the go

Use this textbox to provide one resource that would be a quick read for families on the go.

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

Detailed resource for families who want to learn more

Use this textbox to provide one resource that would be more detailed for families who want to learn more. (Explain why you chose this resource and provide a link.)

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

User-friendly resource for diverse families

Use this textbox to provide one resource that would be user-friendly for diverse families (e.g., ELL, single parents, grandparents raising grandchildren, etc.). (Explain why you chose this resource and provide a link.)

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

Page 9

Use this textbox to write your reflection. In your reflection, be sure to address the following:

Explain your role as an educator in providing developmental activities that support physical, cognitive, and social-emotional growth from 2 months to 2 years.

Describe what it means to be a socially-emotionally competent infant and toddler caregiver.

Discuss how you will foster relationships that promote cognitive and language development in infants and toddlers.

If you use scholarly sources here, add them to the reference list on page 17.

**Delete all the text in this box before you begin your response.


Page 10

Piaget & Vygotsky

Use this textbox to discuss how the theories of Piaget and Vygotsky will influence the ways you support cognitive development in the preschool years. If you use scholarly sources here, add them to the reference list on page 17.

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Learning Centers

Use this textbox to explain your philosophy of why learning centers are a developmentally appropriate method for supporting the physical development of preschoolers. If you use scholarly sources here, add them to the reference list on page 17.

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Use this textbox to describe your philosophy of supporting vocabulary development of preschoolers. If you use scholarly sources here, add them to the reference list on page 17.

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Philosophy of Vocabulary Development

Page 11

Explain three resources for families to support them during the preschool stage of development. Be sure to include a link to each resource.

Quick read resource for families on the go

Use this textbox to provide one resource that would be a quick read for families on the go. (Explain why you chose this resource and provide a link.)

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

Detailed resource for families who want to learn more

Use this textbox to provide one resource that would be more detailed for families who want to learn more. (Explain why you chose this resource and provide a link.)

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

User-friendly resource for diverse families

Use this textbox to provide one resource that would be user-friendly for diverse families (e.g., ELL, single parents, grandparents raising grandchildren, etc.). (Explain why you chose this resource and provide a link.)

* This resource does not count as one of your required scholarly resources and therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

Page 12

Use this textbox to write your reflection. In your reflection, be sure to address the following:

Explain why the development of empathy and sympathy are essential to fostering strong peer relations among preschoolers.

Discuss how you will use information shared with you by families (i.e. historical, biological, environmental, societal, familial, and cultural influences) to support their preschooler’s development.

Describe how you will differentiate instruction to support the unique needs of preschoolers across all developmental domains.

If you use scholarly sources here, add them to the reference list on page 17.

**Delete all the text in this box before you begin your response.


Page 13

The Role of Resilience

Use this textbox to discuss what resilience is and the important role it plays in social-emotional growth during early childhood. If you use scholarly sources here, add them to the reference list on page 17.

**Delete all the text in this box before you begin your response.

Positive Parenting

Use this textbox to explain how positive parenting supports social-emotional growth during early childhood. If you use scholarly sources here, add them to the reference list on page 17.

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Use this textbox to describe how you will utilize brain breaks in your learning environment to support cognitive and social-emotional needs in early childhood. If you use scholarly sources here, add them to the reference list on page 17.

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Brain Breaks in your Learning Environment

Page 14

Explain three resources for families to support them during the early childhood stage (ages 6-8) of development. Be sure to include a link to each resource.

Quick read resource for families on the go

Use this textbox to provide one resource that would be a quick read for families on the go. (Explain why you chose this resource and provide a link.)

* This resources does not count as one of your required scholarly resources & therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

Detailed resource for families who want to learn more

Use this textbox to provide one resource that would be more detailed for families who want to learn more. (Explain why you chose this resource and provide a link.)

* This resources does not count as one of your required scholarly resources & therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

User-friendly resource for diverse families

Use this textbox to provide one resource that would be user-friendly for diverse families (e.g., ELL, single parents, grandparents raising grandchildren, etc.). (Explain why you chose this resource and provide a link.)

* This resources does not count as one of your required scholarly resources & therefore does not need to be included on your reference page.

**Delete all the text in this box before you begin your response.

Page 15

Page 16

Use this textbox to write your reflection. In your reflection, be sure to address the following:

Describe your role in helping families to understand the various influences on child development.

Discuss how developmental theories provide the foundation for early learning, growth, and development.

Explain, using an example, how you will ensure you are implementing developmentally appropriate practice to foster growth and development.

Summarize how you will ensure your learning environment nurtures the physical, socio-emotional, and cognitive growth of diverse learners.

Explain how you revised your handouts from Weeks 1 – 4 based on your instructor’s feedback and additional information you have learned throughout the course.

If you use scholarly sources here, add them to the reference list on page 17.

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Use this textbox for your references. Make sure all references are formatted according to APA Style.

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