CHAPTER 4
PRENATAL
DEVELOPMENT AND
BIRTH
Learning Objectives
• How does development unfold
during the prenatal period from
conception until the time of birth?
• How does prenatal behavior of the
fetus relate to postnatal behavior of
the infant?
Prenatal Development
• Time of fastest development in
life span
• Environment extremely important
• Conception
– Ova travels from ovary to uterus
– Penetration by 1 of 300-500 sperm
– Outcome: Single-celled ZYGOTE
Prenatal Stages
• Germinal period: Days 1-14
– Implantation: One-half are successful
– Miscarriage: 15% to 50%
• Embryonic period: 3rd to 8th week
– Organogenesis, Sexual differentiation
• Fetal period: 9th week – birth
– Proliferation, Migration
– Differentiation of stem cells
– Ends in tremendous brain development
Learning Objectives
• How and when do various teratogens
affect the developing fetus?
• How can you summarize the effects of
teratogens during the prenatal period?
• How do maternal age, emotional state,
and nutrition affect prenatal and neonatal
development?
• What about the father’s state - can this
influence development?
Prenatal Environment
• Reciprocal influence
– Person and environment
– Good and bad influences important
• Teratogen: Environmental agent
– Harms the developing fetus
– Critical Period: Organogenesis
– Dosage and duration
– Genetic make-up: Susceptibility
•
The critical periods of prenatal development. Teratogens are more likely to
produce major structural abnormalities during the third through the eighth
prenatal week. Note, however, that many organs and body parts remain
sensitive to teratogenic agents throughout the nine-month prenatal period
Teratogens: Drugs
• Thalidomide (for morning sickness)
– All or parts of limbs missing
• Tobacco: Miscarriage, low birth weight,
SIDS, slows fetal growth
• Alcohol: FAS
– Small, facial deformities, retardation
• Cocaine: Processing difficulties
• (A) Characteristic features of a child with fetal alcohol syndrome
(FAS).
• (B) Child with FAS, illustrating many features in the drawing.
Such children may also have cardiovascular and limb defects.
Teratogens - Diseases
• Rubella (German Measles)
– Blind, deaf, heart, brain
• Syphilis: Miscarriage, blind, deaf,
heart, brain
– After 18th week
• AIDS: Mothers transmit to babies
(15%-35%)
– Prenatally, perinatally, postnatally
Teratogens: Environmental
Hazards
• Radiation: MR, leukemia, cancer,
mutations, spontaneous
abortions, etc.
– Avoid X-rays when pregnant
• Pollutants
– In air and water
– Lead: MR (also postnatally)
The Mother’s State
• Age: Typically age 16-35
– 15 or younger don’t seek prenatal care
• Birth complications, low birth weight
– Over 35:Miscarriage, Down Syndrome
(father’s age also)
• Emotion: Stress can stunt fetal growth
– Positive outlook most helpful
• Nutrition: 25-35 lb weight gain
– Malnutrition: Smaller neurons, brain, child
The Father’s State
• Research limited except for genetic contribution
• Father’s age can also be influential
– Over 35: Increased number miscarriages,
heart defects, Down Syndrome
– Over 50: Higher risk for schizophrenia
• Exposure to environmental toxins
– Radiation, anesthetic gases, pesticides
– Damage to genetic material in sperm
Postnatal Depression
• Baby Blues: mild, common
• Clinical depression: 1/10
– Previous depression common
• Children of Depressed Mothers
– Insecurely attached, less
responsive
– Negative to other children
The Father’s Experience
• Accepted, expected in delivery
rooms
• Attend prenatal classes with wife
• Experience described as a
significant event
• Anxiety, stress common during
delivery
• Relief, pride, joy when baby is born
The Neonatal Environment
• Culture, early socialization, health status
– E.g., low birth-weight babies (8% in US)
• Less than 5½ lbs
• Strongly linked to low SES
• Environment: Neonatal intensive care
• Risk: Blindness, deafness, CP, autism,
cognitive, and later academic problems
• Parenting must be attentive, responsive
•
Modern technology permits survival of younger and smaller babies, but
many experts believe we have reached the lowest limits of viability at
23-24 weeks gestation.
Learning Objectives
•
•
•
•
What are the advantages of breast feeding?
Are there disadvantages of breast feeding?
How can at-risk newborns be identified?
What treatments are available to optimize
development of at-risk babies?
• To what extent are the effects of the prenatal
and perinatal environments long lasting?
• What factors influence whether effects are
lasting?
Breast or Bottle?
• Breast feeding most natural nutrition
• Practices vary across cultures
• Health benefits great for breast-fed infants
– At least first 6 months recommended
• More likely to bottle feed: Factors
– Younger, low SES, less education,
employed, African American
• US values toward breast feeding
ambivalent
Low Birth-Weight Babies
• < 5½ pounds: “Small for date” or “preterm”
– Leading cause of infant mortality
– 8% of all births, 65% of all infant deaths
• Factors: Low SES, smoking, stress, multiples
• Worse for minority, poverty, single-parent children
• For most, significant catch-up growth
Low Birth-Weight Infants
• Greater risk for blindness, deafness, CP, autism, health
problems - especially respiratory problems
Factors Helpful for LBW Infants
• Breastfeeding, skin-to-skin contact,
massage
• Responsive parenting, intellectual
stimulation
• Early intervention programs work with
parents
– Childcare education and support
– Growth-enhancing home environment
• Consistently attentive, responsive
parenting
Risk and Resilience
• Not all high-risk infants have problems
• Werner: Kauai Longitudinal study (40 yrs)
• Findings:
– Effects decrease over time
– Outcomes depend on postnatal
environment
– Protective factors
• Personal resources
• Supportive postnatal environment