Child Development From Infancy to Adolescence. Laura E. Levine
microcephaly, an abnormally small brain. Pregnant women in areas where this disease occurs need to try to avoid being bitten by mosquitos and to practice safe sex with potentially infected partners.
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Maternal Stress
There are a number of different sources of stress that a pregnant woman might experience. She might be stressed at the prospect of going through the pregnancy, labor, and delivery, or the transition to becoming a parent, which we discuss more fully later in this chapter. She also experiences the day-to-day stress anyone might have and may have some challenging or even traumatic life events during her pregnancy.
Maternal stress. Pregnancy brings with it some unique stresses, but excessive stress from any source can affect the fetus because stress hormones cross through the placenta. What are some things a pregnant woman could do to manage her level of stress?
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Whenever we are under stress, our body produces stress hormones, and one of those hormones, cortisol, can pass through the placenta. In animal studies, maternal stress has been associated with changes in the structure and function of the brain (Buss, Entringer, Swanson, & Wadhwa, 2012). In studies of human mothers, high levels of maternal stress hormones during a pregnancy have been associated with lower birth weight and a slower growth rate in the fetus, and with temperamental difficulties in infants (Wadhwa, 2005). The exact effects depend on the nature, timing, and duration of exposure, but several studies have found that it is maternal stress early in the prenatal period that has a greater impact on fetal growth, length of gestation, infant reactivity to stress, and cognitive development (Davis, Glynn, Waffarn, & Sandman, 2011; Davis & Sandman, 2010; Wadhwa, 2005). Although excessive stress may be harmful, there also is a potentially beneficial effect of an appropriate amount of stress during a pregnancy. The stress inoculation hypothesis suggests that exposure to manageable amounts helps prepare the individual prenatally for challenges that occur after birth (Buss et al., 2012).
Environmental Pollutants
There are any number of toxic chemicals in our homes and workplaces that could be harmful to a pregnant woman (Wilson, 2014). These include household cleaning products, insect repellants, pesticides, and solvents. If possible, pregnant women should not use these products, and if they can’t be avoided, they should be replaced with ones that are less toxic. Pregnant women also can be exposed to lead in the paint used in older homes or from the pipes used in older plumbing. They need to avoid exposure to X-rays, for example from dental exams, and if hazards exist in their workplace, they should talk with their employer and physician about ways to reduce or eliminate this exposure.
A particularly harmful group of chemicals are called endocrine disruptors because they interfere with the functioning of the hormonal system in our bodies and can interfere with the normal functioning of cells (National Institute for Environmental Health Sciences, 2016). When transmitted through the placenta, they affect the development of the part of the brain that controls metabolism and have been associated with an increased risk of certain cancers, abnormal growth patterns, and neurodevelopmental delays in children (World Health Organization, 2016). Women need to educate themselves about the sources of these chemicals which are found in everyday objects such as plastic bottles, detergents, cosmetics, and pesticides, and avoid them whenever possible.
Endocrine disruptors: Chemicals that interfere with the functioning of the hormonal systems of the body.
Although there are a number of factors that can adversely affect prenatal development, there is much a pregnant woman can do to help ensure her own health and the health and well-being of her baby before and after birth. The goal of any pregnancy is a healthy baby and a healthy mother, and fortunately this is exactly what happens in most cases. Although the risks are real and we need to guard against them whenever possible, there also is a great resilience in the developing child. And, as we point out throughout this book, what happens to the child after birth has a huge impact on the eventual developmental outcome. Children who start life with birth defects or developmental deficits benefit greatly from growing up in a nurturing, supportive environment. As you will learn in later chapters, early intervention also can do a great deal to help these children develop to their fullest potential.
Check Your Understanding
Knowledge Questions
1 What can the mother expect during each of the three trimesters of pregnancy?
2 What are the risks to the baby of maternal smoking and drinking during pregnancy?
3 What other factors can pose a risk to the developing embryo or fetus?
Critical Thinking
Choose one of the threats to a healthy pregnancy discussed in this section. Describe how you would make a pregnant woman aware of the risk and what she can do about it, without unnecessarily increasing her stress level.
The Birth Experience
>> LQ 4.3 What happens during the process of labor and delivery?
After months of waiting, the parents-to-be are understandably excited—and likely a bit apprehensive—when labor finally begins. How long the process will take and the mother’s subjective experience of the birth can be quite variable from one woman to the next.
Labor and Delivery
Earlier in the pregnancy the woman may have felt some tightening of the uterine muscles called Braxton Hicks contractions which can begin as early as the 6th week of pregnancy but aren’t noticeable until midpregnancy. They usually are infrequent, painless, and sporadic (Cunningham, Leveno et al., 2014), but as the woman gets closer to her due date, contractions begin to soften and thin out the cervix (the narrow lower end of the uterus) to prepare it for true labor. Labor is divided into three stages: early and active labor, pushing, and delivering the placenta. So much happens during the first stage that it is further divided into three phases: early labor, active labor, and transition. Details about what happens in each stage is provided in Table 4.2, and Figure 4.7 illustrates how the process unfolds.
Early labor: The first phase in the first stage of labor in which contractions are usually not painful but the cervix begins to thin out and dilate.
Active labor: The second phase in the first stage of labor in which contractions become longer, stronger, and more frequent and the cervix dilates to 4 centimeters.
Transition: The third phase in the first stage of labor in which contractions come in rapid succession and last up to 90 seconds each, with little or no pause between them, and which ends when the cervix has dilated 10 centimeters.
Table 4.2
Sources: ACOG (2007); Cunningham, Leveno, et al. (2014).
Figure 4.7 Stages of labor.
As shown in Figure 4.7, most babies enter the birth canal head first, with the back of their head toward the front of their mother’s stomach. Labor can be slower and more difficult if the baby is in an abnormal position, such as facing upward or positioned so the baby’s feet or bottom come out