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CHAPTER 3 CONCEPTION, PRENATAL DEVELOPMENT, AND BIRTH. In this chapter. What happens during the first nine months of development? Will the baby be normal? What should parents do during pregnancy to optimize the baby’s health? What happens during the birth process?.
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In this chapter • What happens during the first nine months of development? • Will the baby be normal? • What should parents do during pregnancy to optimize the baby’s health? • What happens during the birth process?
Conception and the Zygote: The First Two Weeks • Gestation – period from conception to birth • Within hours of conception, the sperm and egg create a zygote. • End of first week differentiation of cells begins. • During second week implantation occurs. • Infertility • Primary factors affecting infertility include health, lifestyle, and age, • Treatments: fertility drugs, artificial insemination, IVF, surrogate mother
Figure 3.1: Changes between 1970 & 2005 in Age When Women Have Their First Child
The Embryo: Weeks Three Through Eight • Specialized layers of cells • Ectoderm • Mesoderm • Endoderm • Organs begin to function • “Primitive streak” • Neurogenesis
The Fetus: Week Eight to Birth • Size of fetus increases twentyfold • The brain and behavior • Some neurons die off as others make new connections. • CNS becomes active and responsive in mid-pregnancy. • Prenatal behavior shapes further brain development. • Learning • Fetuses recognize repeated, familiar sounds. • Individual differences • Differences in heart rate, activity level
Boy or Girl? • Prenatal development • Stage 1 – male and female have similar gonadal streak, Müllerianducts, and Wolffian ducts • Stage 2 – physiological sex differences emerge • Stage 3 – external genitals form; testosterone stimulates development of testicles and penis • Stage 4 – testosterone inhibits the cycles of the hypothalamus and pituitary, which regulate female ovulation
Prenatal Development • Ultrasound imaging • Chromosomal malformations • Caused by mutations or accidents during meiosis • Down Syndrome • Recessive genes • Most genetic disorders carried on a recessive gene • Sickle cell • Hemophilia • The Founder Effect
Genetic Counseling • Beneficial when • member of group know to be at risk • Experienced miscarriage, stillbirth, or infertility • Woman is over 35 • Karyotype • Prenatal testing • Preimplantation genetic diagnosis • Amniocentesis • Chorionic villi sampling
Protecting the Fetus • Maternal characteristics • Age • Diet and nutrition • Stress
Protecting the Fetus • Outside influences • Teratogens • Diseases • Medications • Drinking and smoking • Alcohol • Nicotine • Illicit drugs • Heroin • Cocaine • Environmental toxins
Pregnancy and Parents-to-Be • Experience of pregnancy depends on timing • Women’s concerns over course of pregnancy • Social and emotional challenges of pregnancy
Birth • Labor and delivery • Mother’s pituitary gland releases oxytocin, which triggers uterine contractions. • Labor consists of involuntary contractions. • Stage 1 – cervix opens to 4 centimeters • Stage 2 – baby’s head, then body, pushed into birth canal • Stage 3 – contractions expel placenta
Birth Complications and Controversies • Complications • Anoxia • Cesarean section • Newborns at risk • Preterm • Low birth weight • Respiratory distress syndrome
Infant Assessment • APGAR • Appearance • Pulse • Grimace • Activity • Respiration • Neonatal Behavior Assessment Scale (NBAS)