Prenatal Development and Birth
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Pregnancy is divided into the germinal period, the embryonic period, and the fetal period. During the germinal period, the zygote divides and multiplies until it becomes a blastocyst. The outer shell becomes the placenta, which implants in the uterine lining, and the nucleus becomes the embryo. During the embryonic period, the primitive streak becomes the neural tube, arm and leg buds appear and grow, with hands, feet, fingers, and toes developing in turn. During the fetal period, the genitals differentiate into male and female structures, the brain develops rapidly through neurogenesis and synaptogenesis, and the age of viability is achieved.
The Apgar test is administered one minute after delivery to assess five vital signs: color, heart rate, cry, muscle tone, and breathing on a scale of 0–2. The test is re-
The timing of exposure, the level of exposure, and genetic vulnerability determine the effects of teratogens. If the exposure occurs during a critical period, the level of exposure exceeds the threshold level, or the fetus has a genetic vulnerability, then the teratogen is more likely to have detrimental effects.Anoxia often occurs for a second or two during birth due to compression of the umbilical cord. These brief periods of anoxia rarely cause any effects. Prolonged anoxia can combine with other factors such as genetic vulnerability, teratogens, and maternal infection to increase the likelihood of cerebral palsy.
A new baby becomes a third person in the parents’ relationship, and the parents must adjust to that. By building a parental alliance in which both parents commit to cooperate in raising their child, the couple can work together to protect their relationship and their child.
Birthdays are important. A day or two before every February 28, I send a birthday card to my older brother, a 6-
Prenatal care is important, too. Although my brother was full term, he was born underweight because my mother was told to be hungry when she was expecting. Seventy-
I think both my mother and my daughter were irrational mothers-
My brother often asked what time he was born. My mother always answered that she didn’t remember. Finally, when she was in her 90s, he told her “a story.”
When your first precious baby was beginning to be born, it was February 28th. But labor was slow, so he was born on the 29th. You felt sorry for your little boy, with a birthday only once in four years, so you persuaded the doctor to lie.
“Yes,” Mom replied. “That is just what happened.”
Glen told me that with a smile; he had long suspected my mother’s memory of his time of birth was intact, a few hours past midnight, and that her claim of forgetfulness was to protect a lie. But I was shocked. I thought my scrupulously honest mother would never lie, much less persuade a doctor to sign a false birth certificate. But this illustrates another universal truth: Parents imagine their newborns’ future lives and try to protect them.
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In this chapter, you will learn about the amazing growth of the embryo and fetus, and you will learn how family members and medical professionals safeguard newborns. Possible harm is noted, too—