1. Prenatal Development and Birth
Chapter Four
Prenatal Development and Birth
From Zygote to Newborn
Risk Reduction
Birth

2. From Zygote to Newborn
Prenatal development is divided into three main periods:
germinal period (0-2 weeks)
embryonic period (3-8 weeks)
fetal period (9 weeks-birth)

3. Germinal: The First 14 Days
germinal period:
first two weeks of prenatal development after conception
Characterized by rapid cell division and the beginning of cell differentiation.

4. embryonic period: fetal period:
approximately the third through eighth week after conception
all body structures, including internal organs, begin to develop
fetal period:
stage of prenatal development from ninth week after conception until birth, during which the organs grow in size and mature in functioning

5. Germinal: The First 14 Days
implantation:
process in which developing organism burrows into placenta that lines uterus
placenta:
organ that surrounds developing embryo and fetus, sustaining life via the umbilical cord

6. Embryo: From the Third Through the Eighth Week
name for a developing human organism from about the third through the eighth week after conception

7. Fetus: From the Ninth Week Until Birth
The developing organism is called a fetus from the start of the ninth week after conception until birth.
during the fetal period the fetus develops from tiny, sexless creature to a 7 1/2-pound, 20-inch boy or girl

8. The Third Month
At the end of the third month, the fetus has all its body parts.
Weighs approximately 3 ounces, and is about 3 inches long.
Early prenatal growth is very rapid, but there is considerable variation from fetus to fetus, especially in body weight.

9. In the fourth, fifth and sixth months:
heartbeat becomes stronger
cardiovascular system becomes more active
brain increases about six times in size

10. In the final three months of prenatal life:
age of viability:
Age at which a fetus can survive outside the mother’s uterus if specialized medical care is available.
about 22 weeks after conception
In the final three months of prenatal life:
brain waves indicate responsiveness.
lungs expand and contract, using the amniotic fluid as a substitute for air.
heart valves, arteries, and veins circulate the fetal blood.

12. Risk Reduction teratogens: agents and conditions that can:
harm the prenatal brain
impairing the future child’s intellectual and emotional functioning

13. Determining Risk
Once it was thought the placenta screened out all harmful substances.

14. The effort to understand what triggered such damage gave rise to:
teratology: science of risk analysis, the study of birth defects

15. Timing of Exposure

16. Second important factor is the dose and/or frequency of exposure.
threshold effect: situation in which a certain teratogen is relatively harmless in small doses but harmful once exposure reaches certain level (the threshold)
interaction effect: result of a combination of teratogens
Sometimes risk is greatly magnified when embryo or fetus is exposed to more than one teratogen at the same time.

17. Genetic Vulnerability
Several lines of evidence suggest that genes may be crucial.
Dizygotic twins, exposed to same teratogens but have only half their genes in common, are born with different abnormalities.
Suggests both protective and vulnerable genes.
Cleft lip, cleft palate, club foot more common in some families.
Suggests genetic vulnerability.

18. Protective Measures
Impact of teratogens cannot be predicted before mid-pregnancy.
Some pregnant women are exposed to the tetragons with no evident harm.

19. A View From Science Alcohol in high doses is a proven teratogen.
40 years ago drinking during pregnancy was believed to be harmless.
Obstetricians noted that some patients who drank heavily while they were pregnant had babies with distorted faces.
fetal alcohol syndrome (FAS)
fetal alcohol effects (FAE)

20. fetal alcohol syndrome (FAS): cluster of birth defects, including:
abnormal facial characteristics
slow physical growth
retarded mental development
fetal alcohol effects (FAE): condition in which child has been exposed to alcohol before birth
has some signs of fetal alcohol syndrome but does not meet all the criteria

21. Benefits of Prenatal Care
Tests done during pregnancy can diagnose problems early on, and remedies can be put in place in some instances.
sonogram: image of unborn fetus (or an internal organ) produced by high-frequency sound waves (ultrasound)

22. For full-term fetus and a healthy mother, birth can be simple and quick.

23. The Newborn’s First Minutes
Most newborns begin to breathe as soon as their head emerges.
first breath causes infant’s color to change
eyes open wide
the tiny fingers grab
toes stretch and retract
mucus in the baby’s throat is removed
umbilical cord is cut to detach the placenta
placenta is expelled

24. Apgar scale: quick assessment of newborn’s condition including:
the baby’s color
heart rate
reflexes
muscle tone
respiratory effort
Appearance, Pulse, Grimace, Activity, Respiration

25. Medical Intervention
about 31% of births in the U.S. are cesarean section, (also called c-section)
incision through mother’s abdomen and uterus to allow fetus to be removed quickly, instead of being delivered through the vagina

26. Birth In Developing Nations
In the U.S. only 1% of births take place at home.
Worldwide most births occur at home.
doula- a woman who helps with the birth process
- also helps with breastfeeding and newborn care.

27. Anoxia anoxia: cerebral palsy:
lack of oxygen that can cause brain damage or death to the baby
means “no oxygen”
cerebral palsy:
disorder that results from damage to brain’s motor centers
People with cerebral palsy have difficulty with muscle control, so their speech and body movements are impaired.

28. Low Birthweight (LBW) Average weight of a newborn is 7½ lbs.
low birthweight (LBW): a body weight at birth of less than 5½ lbs.
very low birthweight (VLBW): a body weight at birth of less than 3 lbs, 5oz.
extremely low birthweight (ELBW): a body weight at birth of less than 2 lbs, 3 oz.

29. preterm birth: occurs 3 or more weeks before full 38 weeks of a typical pregnancy
Preterm babies are typically (but not always) LBW because they miss final weeks of weight gain.
small for dates or small for gestational age (SGA)- birth weight is lower than expected given the time of conception.

30. Social Support The developing person is affected by quality of:
medical care
education
culture
social support
Fathers and other relatives, neighbors, cultures, and, clinics can reduce risk of birth complications

31. Mothers, Fathers, and a Good Start
Birth complications can have a lingering impact on the new family, depending partly on:
sensitivity of hospital care
the home
To reduce stress on an infant who has to stay in the hospital, parents are encouraged to help with early caregiving.

32. kangaroo care: form of child care in which the mother of a low-birthweight infant spends at least an hour a day holding the baby between her breast, like a kangaroo

33. Help from Fathers
Fathers can be crucial in the effort to produce a healthy baby.
Supportive father-to-be helps a mother-to-be:
stay healthy
well nourished
drug-free

34. parental alliance: cooperation between a mother and a father based on mutual commitment to their children
Parents agree to support each other in their shared parental roles.

35. Postpartum Depression
new mother’s feelings of inadequacy and sadness in days and weeks after giving birth including:
irritability
eating disruptions
sadness
feeling overwhelmed and inadequate
affects 10-15% of women

36. Bonding
parent-infant bond: strong, loving connection that forms as parents hold, examine, and feed newborn
cross-fostering: newborns are removed from their biological mothers in first days of life and raised by another female or even male