chapter summary:

Prenatal Development

• Nature and nurture combine forces in prenatal development. Much of this development is generated by the fetus itself, making the fetus an active player in its own progress. Substantial continuity exists between what goes on before and after birth in that infants demonstrate the effects of what has happened to them in the womb.
• Prenatal development begins at the cellular level with conception, the union of an egg from the mother and a sperm from the father to form a single-celled zygote. The zygote multiplies and divides on its way through a fallopian tube.
• The zygote undergoes the processes of cell division, cell migration, cell differentiation, and cell death. These processes continue throughout prenatal development.
• When the zygote becomes implanted on the uterine wall, it becomes an embryo. From that point, it is dependent on the mother to obtain nourishment and oxygen and to get rid of waste products through the placenta.
• Fetal behavior begins 5 or 6 weeks after conception with simple movements, undetected by the mother, that become increasingly complex and organized into patterns. Later, the fetus practices behaviors vital to independent living, including swallowing and a form of intrauterine “breathing.”
• The fetus experiences a wealth of stimulation both from within the womb and from the external environment. The fetus learns from this experience, as demonstrated by studies showing that both fetuses and newborns can discriminate between familiar and novel sounds, especially in speech, and exhibit persistent taste preferences developed in the womb.
• There are many hazards to prenatal development. The most common fate of a fertilized egg is spontaneous abortion (miscarriage). A wide range of environmental factors can be hazardous to prenatal development. These include teratogens from the external world and certain maternal characteristics, such as age, nutritional status, physical health, behavior (especially the use of legal or illegal drugs), and emotional state.

The Birth Experience

• Approximately 38 weeks after conception, the baby is ready to be born. Usually, the behavior of the fetus helps to initiate the birth process.
• Being squeezed through the birth canal has several beneficial effects on the newborn, including preparing the infant to take his or her first breath.
• Cultural practices surrounding childbirth vary greatly and are in part related to the goals and values emphasized by the culture.

The Newborn Infant

• Newborns’ states of arousal range from deep sleep to active crying.
• The amount of time infants spend in the different arousal states varies greatly, both across individuals and across cultures.
• REM sleep seems to compensate for the lack of visual stimulation that results from the darkness of the womb, and for the fact that newborns spend much of their time with their eyes shut, asleep.
• The sound of a baby crying can be very aversive, and adults employ many strategies to soothe distressed infants.
• The infant mortality rate in the United States is high relative to that of other developed countries. It is much higher for babies born to low-SES parents.
• Infants born weighing less than 5½ pounds (2500 grams) are referred to as being of low birth weight. LBW infants are at risk for a variety of developmental problems, and the lower the birth weight, the greater the risk of lasting difficulties.
• A variety of intervention programs have been designed to improve the course of development of LBW babies, but the success of such programs depends very much on the number of risk factors that threaten the baby.
• The multiple-risk model refers to the fact that infants with a number of risk factors have a heightened likelihood of continued developmental problems. Poverty is a particularly insidious risk to development, in part because it is associated with numerous negative factors.
• Some children display resilience even in the face of substantial challenges. Resilience seems to result from certain personal characteristics and from responsive care from someone.