ITRG – Preparing the Environment (hhs.gov) ITRG – Reflective Exercise: Experience Your Space from the Perspective of an Infant or Toddler (hhs.gov) Science of Babies – Video – Films O
We often think of human development in terms of milestones and various ages, but development actually begins in the womb. This week, you will continue to support Paul and Amy from Week 1 and provide them with information to help support them in their parenthood journey. Remember, a Milestones Table appears at the end of each age division of the text.
To prepare for this discussion,
· Read Chapter 3: Prenatal Development
· Read Chapter 4: Birth and the Newborn Baby
· Read Preparing the Environment Links to an external site.
· Watch Science of BabiesLinks to an external site.
For this discussion, you will utilize the case study below:
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Case Study Paul and Amy have learned that they are expecting a baby. They could not be more thrilled, but like most newly expectant parents, they are trying to learn as much as they can before their newborn arrives. They have been reading many different resources to better understand the various factors that will influence the development of their child while in the womb and how to manage those first few weeks with a newborn. |
In your initial post,
· Discuss whether you think newborns are more competent than you thought they were before you read Chapter 4 of the course text.
· Describe which of the newborn capacities (i.e., reflexes, states of arousal, or sensory capacities) were the most surprising to you.
· Describe two factors, within and beyond the family, that can help families feel supported during the prenatal and newborn stages of development.
,
CHAPTER 3 PRENATAL DEVELOPMENT
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
WHAT’S AHEAD IN CHAPTER 3
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 MOTIVATIONS FOR PARENTHOOD
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)
ADVANTAGES
DISADVANTAGES
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.
© LAURA DWIGHT PHOTOGRAPHY
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 PRENATAL DEVELOPMENT
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.
© PASCAL GOETGHELUCK/Science Source
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.
Implantation
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
Trimester
Prenatal Period
Weeks
Length and Weight
Major Events
First
Germinal
1
2
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.
Embryo
3–4
5–8
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.
Fetus
9–12
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.
Second
13–24
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.
Third
25–38
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.
© LENNART NILSSON, A CHILD IS BORN/TT NYHETSBYRÅN
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
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