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Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Chapter 4
Prenatal Development and Birth
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Chapter 4- Prenatal Development
• Time of fastest development in life span
• Environment extremely important
• Conception
– Ova (eggs) travels from ovary to uterus
– Penetration by 1 of 300-500 sperm
– Outcome: single-celled ZYGOTE (fertilized
egg)
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Prenatal Development and the Zygote
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
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Prenatal Stages
Germinal period: days 1-14 (0 - 2 weeks)
– Zygote’s implantation into uterine wall: 1/2 are
successful
– Zygote divides many times through mitosis to form
blastocyst (about 150 cells)
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– Miscarriage: 15% (recognized) to 50%
Embryonic period: 3rd to 8th week (3rd week - 2nd month)
– Organogenesis – every major organ takes shape
– Sexual differentiation – begins during 7th & 8th week
(sex genes impact formation of testes or ovaries)
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Outer Layer of Blastocyst (150 cells) forms:
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Amnion – a watertight membrane that fills with fluid that
cushions and protects the embryo
Chorion – a membrane that surrounds the amnion and
attaches rootlike extensions called villi to the uterine lining to
gather nourishment for the embryo. The chorion eventually
becomes the lining of the placenta
Placenta – tissue fed by mother’s blood vessels and
connected to the embryo by the umbilical cord
Umbilical cord – connection between embryo and mother
through which nutrients and wastes are exchanged
Placental barrier – protects developing child from many
harmful substances, and allows small molecules exchanged
between mother and embryo
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Inner cell mass of blastocyst forms:
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Ectoderm – eventually forms the central nervous
system (brain and spinal cord)
Mesoderm – muscle tissue, cartilage, bone,
heart, arteries, kidneys, and gonads
Endoderm – gastrointestinal tract, lungs, and
bladder
Neural plate forms neural tube (bottom is spinal
cord)
Top of tube forms into forebrain, midbrain, hindbrain
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Figure 4.3
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
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Fetal period: 9th week – birth
– Proliferation of neurons (250,000 per minute)
– Migration of neurons
– Differentiation of stem cells
– Ends in tremendous brain development
Age of viability – around 24-25 weeks (fetus has possibility
of surviving outside uterus)
3rd Trimester – myelination (insulating cover that increases
speed of transmission)
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Prenatal Development and the Newborn
40 days
45 days
2 months
4 months
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Prenatal Environment
• Reciprocal influence
– Person and environment
– Good and bad influences important
• Teratogen: harmful environmental agent
– Harms the developing fetus
– Critical Period: Organogenesis
– Dosage & duration
– Genetic make-up: susceptibility
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Teratogens-Drugs
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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
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Figure 4.6
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
FETAL ALCOHOL SYNDROME
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
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
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Teratogens – Environmental Hazards
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Radiation: MR, leukemia, cancer, mutations,
spontaneous abortions, etc.
– Avoid X-rays when pregnant
Pollutants
– In air and water
– Lead - MR (also postnatally)
Anoxia – Oxygen shortage – brain cells die – can cause
mental retardation or cerebral palsy (difficulty
controlling muscle movements and possibility of MR)
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
Postnatal Depression
• Baby Blues, mild, common
• Postpartum depression: 1/10
– Previous depression common
• Children of depressed mothers
– Insecurely attached, less responsive
– Negative to other children
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
APGAR TEST
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Provides a quick assessment of the newborn’s:
1)Heart rate (0-2 points)
2)Respiratory effort (0-2 points)
3)Muscle tone (0-2 points)
4)Color (0-2 points)
5)Reflex irritability (0-2 points)
The Apgar test is given immediately and 5 minutes after birth
7 or higher = good shape
4 or lower = at risk
Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. Rider
Chapter 4
The Neonatal Environment
• Culture, early socialization, health status
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– E.g., low birth-weight babies (8% in US)
• Less than 5 1/2 lbs or 2500 grams
• Strongly linked to low SES
• Environment: neonatal intensive care
• Risk: blindness, deafness, CP, autism,
cognitive, and later academic problems
Parenting must be attentive, responsive