CHAPTER OUTLINE
I.
Prenatal development
A. Conception
Midway
through menstrual cycle ovum is released
a. egg usually disintegrates
b. if woman has intercourse 300 million sperm
enter body
i. 6-hour
journey to fallopian tubes
ii.
one sperm may enter the egg
iii.
biochemical reaction keeps other sperm
from entering egg
iv.
conception has taken place
B. Prenatal Stages
1. Lasts for about 266 days (9 months)
a. zygote to fetus – one cell to billions
b. prenatal development occurs in three stages
i. germinal
period
ii.
period of embryo
iii.
period of fetus
2. The germinal period
a. lasts about 2 weeks
b. zygote divides to form blastula
i. hollow
ball of 150 cells
ii.
size of head of pin
c. as many as 50% terminate
3. The embryonic period
a. lasts from the third to eighth week
b. organogenesis-- every major organ takes shape
c. blastocyst forms layers
i. amnion--
watertight membrane surrounding
ii.
chorion-- membrane on outside of amnion
containing villi that
attach
to uterine lining
iii.
placenta-- tissue fed by mother’s blood
vessels
iv.
umbilical cord-- connection between
embryo and mother
through
which nutrients and wastes are exchanged
v. placental
barrier-- membrane through which molecules pass
vi. ectoderm, mesoderm, and endoderm layers
d. brain development apparent after three to
four weeks
i. neural
plate forms neural tube (bottom is spinal cord)
ii.
top of tube forms into forebrain,
midbrain, hindbrain
iii.
spina bifida-- spinal cord fails to
become fully enclosed
iv.
anencephaly-- tube at top fails to
close, main portion of brain
fails
to develop
v.
encephalocele-- brain protrudes from
skull
e. organs (e.g., heart, eyes) take shape
f. arms and legs appear
g. sexual differentiation
i. about
seventh to eighth prenatal week, sex genes impact
formation
of testes or ovaries
ii.
secretion of testosterone by male
embryo stimulate male
system
and inhibits female system
iii.
absence of correct hormones negatively
impacts development
4. The fetal period
a. ninth prenatal week to birth
b. significant brain development
i. proliferation
of neurons (250,000 per minute)
ii.
significant development between 10 and
20 weeks
iii.
increase in number of glial cells
iv.
neurons migrate into position
v. neurons
begin to differentiate in function
vi.
early cells known as stem cells
c. sex and sensory organs, bones, muscles, body
systems
d. second trimester (months 4-6)
i. refined
activities
ii.
sensory organ development
e. age of viability-- around 24-25 weeks after
conception has possibility
of surviving outside uterus
f. third trimester (months 6-9)
i. rapid
growth in length and weight
ii.
brain development-- myelination
iii.
infant states-- organization of behavior
in waking and sleeping patterns
iv.
beginning of continuity between prenatal
and postnatal
behavior
v. contractions
of uterus typically begin birth process
II.
The prenatal environment
Mother’s
womb is environment for unborn child
1940’s
belief that placenta protected embryo and fetus from hazards
New
focus on environmental factors that negatively impact prenatal development
A. Teratogens
1. Teratogens-- disease, drug, or environmental
agent that can harm prenatal
organism
generalizations
concerning teratogens
i. effects
are worst during critical period when organs are forming
ii.
effects determined by dosage and
duration of exposure
iii.
susceptibility is influenced by genetic
makeup of mother and
fetus,
and the quality of the prenatal environment
iv.
prenatal and postnatal environments determine
impact
v. critical
periods-- times when organism is highly sensitive to
damage
(also called sensitive periods)
2. Drugs
a. thalidomide
i. used
in 1950s for relief of morning sickness
ii.
major impact (e.g., flipper limbs,
deformed ears, missing thumbs) if taken between 20 and 35 days
iii.
banned but now being used to treat other
disorders (e.g., cancer)
b. tobacco
i. despite
warnings about 15% of pregnant women smoke
ii. inhibits
prenatal growth, increases risk of miscarriage, retard
grow
of fetus
iii.
passive smoke also harmful
iv.
increases odds of sudden infant death
syndrome
c. alcohol
i. fetal
alcohol syndrome-- cluster of symptoms (e.g., small size,
distinct
facial features) associated with alcohol consumption
by
pregnant women
ii.
increased risk for hyperactivity,
seizures, mental retardation,
attention
deficit
iii.
30% of pregnant women drink
iv.
binge drinking and continuous patterns
both can have negative
impact
v. genetic
and environmental factors (e.g., smoking, malnutrition)
may
mediate impact
d. cocaine
i. damage
includes spontaneous abortion, sensory skill deficits,
respiratory
difficulty
ii.
parental behaviors may also contribute
to impact of cocaine
3. Diseases
a. rubella-- German measles
i. impact: blindness, deafness, heart defects, and
retardation
ii.
impact greatest during first trimester
iii.
immunizations critical
b. syphilis
i. sexually
transmitted
ii.
impact includes blindness, deafness,
heart defects, and
retardation
iii.
impact greatest late in pregnancy--
cannot cross placental
barrier
until 18th week
c. AIDS-- acquired immune deficiency disorder
i. caused
by HIV
ii.
destroys immune system
iii.
transmitted prenatally, perinatally,
postnatally (breastfeeding)
iv.
mother-to-child transmission in
peak
4. Environmental hazards
a. radiation
i. leads
to mutation
ii.
take care with X-ray
b. pollutants
i. heavy
metals (e.g., lead) (e.g., lead) can have prenatal impact
ii.
chemistry of prenatal environment can
have major impact on
development
B. The Mother's State
1. Age
a. ages 16-35 are "safest"
childbearing years
b. younger risk due to immature reproductive
system and poor medical
care
c. older risk due to miscarriage for often
unknown reasons
2. Emotional condition
a. prolonged, severe emotional stress may be
damaging
b. damage may be due to stress hormones
c. presence of stress not as important as
reaction to stress
d. anxiety and depression may also have impact
3. Nutritional condition
a. recommend 25 to 35 pound weight gain (normal
weight women)
b. malnutrition can lead to birth defects
i. first trimester
malnutrition impact brain and spinal cord
ii.
third trimester impact is smaller
neurons, brain, and child
c. prenatal malnutrition impact may lead to
predisposition to adult
diseases
d. adequate levels of folic acid important
C. The Father’s State
Little
research on father’s contribution (beyond genetic)
paternal
age (over 40) may be risk factor
i. risk
of Down syndrome higher for older men
ii.
exposure to environmental toxin also
increases risk
III.
The perinatal environment
Perinatal
environment-- social and medical environment surrounding birth
Birth
has become more medicalized
Use
of supports like partners or doulas is on the rise
Presence
of supports leads to more positive birthing experience
A. Birth is Three-Stage Process
1. Contractions of uterus and dilation of cervix
a. duration average of 6 to 7 hours
b. ends with dilation of cervix of 10
centimeters
2. Delivery of baby
a. fetus passes out of uterus
b. fetus emerges from woman’s body via the
vaginal opening
3. Delivery of placenta
4. Participants often exhausted
B. Possible Hazards
1. Anoxia-- oxygen shortage (also called
asphyxia)
a. umbilical cord pinched or tangled
b. mucus in baby’s throat
c. sedatives given to mother
d. can cause mental retardation
e. can cause cerebral palsy-- neurological
disability inhibiting movement
f. brief periods of anoxia typically harmless
g. breech position (feet or buttocks first)
increases risk of anoxia
i. may
prohibit vaginal delivery
ii.
may lead to cesarean section-- surgical
removal of baby
2. Complicated delivery
a. forceps-- salad tong-like instrument used to
help extract baby
b. vacuum extraction-- “suction-cup” device used
to help extract baby
c. cesarean section (C-section) controversial
but process is safe
i. account
for 26% of
ii.
used to protect physician against
malpractice suits
iii. planned C-section better than unplanned
iv. more revenue (expensive) than vaginal
delivery
v.
controversial case of mother being
forced to use C-section
3. Medications
a. sedatives can affect baby
b. regional analgesics (epidural or spinal
block) deaden pain in area of
body and have less affect on baby
C. The Mother’s Experience
1. Psychological factors
attitude,
knowledge, sense of control, support impact experience
2. Cultural factors
a. desirability to have children varies by
culture
b. birth practices differ by culture
Kenyan
families celebrate, dad stops hunting, baby given ash and
herbs
to vomit amniotic fluid, mom given time to recover
c. Northern Indian childbirth seen as polluting
and treated as shameful act
(due to blood)
i. poorly
trained and hateful dai helps deliver baby
ii.
baby’s hair is shaved off
d. Western societies have “medicalized”
childbirth and infant mortality
rates have dropped morality rates
significantly higher for black infants
3. Postpartum depression
a. baby blues-- feelings of anxiety,
irritability, and depression common for
a few days after birth but typically fades
b. postpartum depression-- more serious
post-birth feelings of anxiety,
moodiness, and depression experienced by
some women in months
after birthing
c. postnatal depression rare but serious (tends
to be found in women with
history of depression or who few social
supports
d. most women recover from postnatal depression
but it may continue to
influence mother-child interactions
e. children of postnatally depressed mothers may
exhibit behavioral
problems (e.g., violence) during late
childhood and adolescence
f. professional help may be needed to overcome
depression
D. The Father’s Experience
1. Western society fathers historically excluded
from birth process
2. Impact both positive and negative
IV.
The neonatal environment
Neonatal environment-- emphasis on newborn time of life
1. Cross-cultural variation in beliefs
concerning newborns
a. The Bengs view newborn as not of this world
until after umbilical cord
falls off (achieve full inhabitance around
age 4-5 years)
b. The !Kung carry infant in slings and are
indulged well into life
breast-fed until age 4 years
c. Myan mothers sleep in bed with infant until
they are toddlers
2. Brazelton Neonatal Behavioral Assessment--
newborn assessment scale
a. assess reflexes and responses to 26
situations
b. test used to teach parents how to be
responsive to infants
A. Identifying High-Risk Newborns
1. At-risk status may be due to genetic,
prenatal hazards, or perinatal damage
2. Apgar test-- used to assess newborn status
a. assesses factors of heart rate, color, muscle
tone, respiration, and
reflexes
b. score of 0, 1 or 2 for each factor
c. Apgar score of 7-10 good, 6 to 5 ok, less
than 4 not good
3. Low birth weight babies
a. weigh less than 2,500 grams or 5 1/2 pounds
at birth
b. some are full-term and some are preterm
c. great increase in risk of infant death
d. linked to socioeconomic status
prevention
programs target health condition associated with
poverty
e. smoking and maternal stress contribute to
low-birth-weight
f. associated with multiple births
i. increase
in multiple births in part due to greater use of
ovulation
stimulating
drugs
ii.
higher-order multiple births (3 or more
children) have increased dramatically in past decades
g. with neonatal care many low-weight babies
survive
h. surfactant-- substance that prevents air sacs
in lungs from sticking
together and allows for breathing
i. cerebral palsy more common neurological
problem for low-birth-weight
infants
j. fate of low-birth-weight infants depends on
biological condition and
parental responsiveness
k. intervention programs like Infant Health and
Development Program
benefit low-birth-weight infants
i. emphasis
on growth-enhancing home environment
ii.
linked to increased IQ score in
childhood
l. responsive parenting critical
B. Risk and Resilience
1. Werner and Smith longitudinal study of
Hawaiian infants
a. children classified into risk groups
b. resilience-- ability to get back on course of
normal development
i. effects
of prenatal and perinatal complications decrease over
time
ii.
quality of postnatal environment
determines outcome of early
risk
2. Protective factors-- factors that help children
overcome disadvantage
a. personal resources-- intellectual,
sociability, and communication traits
that help one cope
b. supportive postnatal environment-- social
support from environment
environment
matters throughout life