Chapter 4 – Prenatal Development and Birth Prenatal Growth

1. Chapter 4 – Prenatal Development and BirthPrenatal Growth • Germinal Period (1st two weeks after conception): rapid cell division and beginning of cell differentiation • Embryonic Period (3rd through 8th week): basic forms of all body structures develop • Fetal Period (9th week until birth): fetus grows in size and matures in functioning

2. The Germinal Period • Zygote begins duplication and division within hours of conception • Development of the placenta • Organ that surrounds the developing embryo • Sustains life via the umbilical chord • Implantation (about 10 days after conception) • Developing organism burrows into the placenta that lines the uterus

3. The Germinal Period

4. The Embryonic Period Embryo • 3rd through the 8th week after conception • Begins when the primitive streak appears down the middle of the cell mass • Primitive streak becomes the neural tube and later the brain and spinal column • Eyes, ears, nose, and mouth form • Heart begins to pulsate • Extremities develop and webbed fingers and toes separate

5. The Embryonic Period

6. Fetus 9th week after conception until birth Genitals form and sex hormones cause differences brain organization Cephalocaudal and proximodistal growth Heartbeat detectable via stethoscope Cortex is not fully mature at birth Brain at birth is biggest part of baby The Fetal Period

7. Age of viability Age at which a preterm newborn may survive outside the womb with medical care About 22 weeks after conception Brain is able to regulate basic body functions Chances of survival increase with each day after the 22-week mark The Fetal Period

8. The Fetal Period

9. Birth • Fetal brain signals the release of hormones to trigger the mother’s uterine muscles • Labor begins • Average duration for first babies: 12 hours • Quicker labor for later babies • Apgar scale • Quick assessment of newborn’s heart rate, breathing, muscle tone, color, and reflexes • Completed twice (1 minute and 5 minutes after birth) • Score of 0, 1, or 2 in each category • Desired score: 7 (total) or above

10. A Normal, Uncomplicated Birth

11. Birth

12. Medical Assistance Cesarean Section (c-section) • Surgical birth • Fetus can be removed quickly • Rates and reasons for c-sections vary • Lower rates in poorer countries • Higher rates in richer countries • 1/3 of births in the United States • Less trauma for the newborn but slower recovery for the mother • Subsequent cesarean deliveries may be necessary

14. Newborn Survival • Infant mortality has decreased due to better medical care • 1900: 5% • Today: <1 in 200 • Childbirth has become safer for mothers • Death rate in poorest nations: 1 in 20 women • Excessive medical care also has disadvantages • Increase in unnecessary c-sections is associated with higher rate of low-birth weight babies

15. Traditional and Modern Birthing Practices • Home births • Hospital births • Doula • Woman who helps with labor, delivery, breast-feeding, and newborn care • May be related to lower rate of cesarean sections

16. Harmful Substances • Teratogens • Substances and conditions that can impair prenatal development and result in birth defects or even death • Not all teratogens can be avoided • Structural abnormalities are obvious at birth • Behavioral teratogens • Affect the child’s developing brain • Developmental retardation, hyperactivity, and learning disabilities • Effects do not become evident for months or years

17. Risk Analysis • Knowing which risks are worth taking • How to minimize chance of harm • Teratology: science of risk analysis • Threshold effect: when a teratogen is harmless in small doses but becomes harmful at a certain level (threshold)

19. Applying the Research • Fetal alcohol syndrome (FAS) • A cluster of birth defects including abnormal facial characteristics, slow physical growth, and retarded mental development • May occur in the child of a woman who drinks alcohol while pregnant

20. Low Birthweight • Low birthweight (LBW) • Less than 2,500 grams (5½ pounds) at birth • United States • Steady increase in LBW over the past 25 years • 8% of newborns are seriously underweight • More susceptible to teratogens, higher birth risks, lower survival rate • Very low birthweight (VLBW) • Under 1,500 grams (3 pounds, 5 ounces) at birth • Extremely low birthweight (ELBW) • Under 1,000 grams (2 pounds, 3 ounces) at birth

21. Preterm or Slow Growing? • Preterm • Birth that occurs at 35 or fewer weeks after conception • Usually associated with low birthweight • Small for gestational age (SGA) • Birthweight is significantly lower than expected, given the time since conception • Suggests impairment throughout prenatal development and serious problems

22. Complications During Birth • Cerebral palsy: -damage to the brain’s motor centers -speech and/or muscles are impaired • Anoxia: -lack of oxygen -over time can cause brain damage or death

23. The Newborn • Brazelton Neonatal Behavioral Assessment Scale (NBAS) • A test that measures responsiveness • records 46 behaviors, including 20 reflexes

24. Moving and Perceiving The Newborn • The first movements are not skills but reflexes, involuntary responses to a particular stimulus.

25. The Newborn Some reflexes aid survival • breathing • thrashing • shivering • sucking • rooting • swallowing • spitting up

26. The Newborn Other reflexes signify normal functioning: • Babinski reflex. When feet are stroked, their toes fan upward. • Stepping reflex. When held upright with feet touching a flat surface, infants move their legs as if to walk. • Swimming reflex. When laid horizontally on their stomachs, infants stretch out their arms and legs. • Palmar grasping reflex. When something touches infants’ palms, they grip it tightly. • Moro reflex. When someone startles them, infants fling their arms outward and then bring them together on their chests, as if to hold on to something, while crying with wide-open eyes.

27. The Father’s Role • Supportive father helps mother stay healthy • Father can decrease or increase mother’s stress (affects fetus) • Most fathers are helpful to their pregnant wives • Two way street: Pregnant mothers should support, involve, and encourage fathers

28. The Father’s Role • Couvade: symptoms of pregnancy and birth experienced by fathers • Parental alliance: • cooperation between a mother and a father based on their mutual commitment to their children • the parents support each other in their shared parental roles.

29. Postpartum Depression • Sadness and inadequacy felt by 8-15% of new mothers in the days and weeks after giving birth • Symptoms range from baby blues to postpartum psychosis • baby care feels burdensome and thoughts of mistreating the infant may exist • Paternal involvement can have beneficial effect • Some fathers are depressed themselves • Causes for Postpartum Depression vary

30. Bonding Parent-Infant Bond • The strong, loving connection that forms as parents hold, examine, and feed the newborn • Early skin-to-skin contact is not essential • Cross-fostering in monkeys • Newborns are removed from their mothers and raised by another female or male • Strong and beneficial relationship sometimes develops

31. Bonding • Birth complications can have lingering impact on later life • Mothers and fathers should help with early caregiving if newborn must stay in the hospital • Kangaroo care • Child-care technique in which the mother of a LBW infant holds the baby between her breasts • Allows baby to hear mother’s heartbeat and feel her body heat • Research confirms beneficial effects