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Higher order question: What factors influence how severely teratogens influence the developing organism? Most vulnerable in the early stages of pregnancy More frequent exposure and higher doses =
more severe damage Poor nutrition, lack of prenatal care, and
presence of multiple teratogens can worsen effects
Effect depends on organism: Thalidomide: human fetus extremely sensitive; no effect on
rats or rabbits
Importance of timing of exposure: During the zygote period: Fluids do not mix with mother’s,
not as susceptible. Embryonic period: Organs are forming and are especially
vulnerable. Fetal period: Growth retardation and tissue damage.
Rubella in mothers affect 2-3% in the zygote period; 50% in the early embryo period (1st month); 22% in the late embryo period (2nd month); 6-8% in the early fetal period (3rd month).
What factors influence how severely teratogens influence the developing organism?
What common teratogens haven’t been discussed?
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Alcohol: F e t a l A lc o h o l S y n d r o m e ( F A S ) : A
cluster of abnormalities that appear in the offspring of mothers who drink alcohol heavily during pregnancy
Fetal Alcohol Syndrome
Facial abnormalities Heart problems Lower IQ
Developmental lag Poor attention Poor social skills
Study on effects of moderate drinking (Streissguth, 1989)
Low versus moderate consumption of alcohol Less than 1.5 oz (1/4 glass) alcohol/day More than 1.5 o z alcohol/ day
Design features: Large sample (n= 421) Longitudinal (prenatal to 4 yrs old) Control for: education race, smoking, aspirin,
antibiotics, illicit drugs, sex & birth order, preschool attendance
Findings: Moderate consumption lowers IQ by 4
points 3 times greater risk for IQ lower than 85
by age 4 Poor heart and lung function at birth
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Alcohol interferes with migration of neurons during brain development
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Amount of alcohol ingested does not uniquely determine severity of FAS
Susceptibility is affected by the mother’s physiological state: Age Nutritional status Overall health, etc.
Effects of agents on the mother might be negligible or temporary
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M a r i ju a n a : Growth retardation Premature birth Poorer verbal and memory development at 4 years of age
C o c a in e a n d C r a c k : Growth retardation Spontaneous abortion Premature birth Withdrawal symptoms such as tremors and irritability
H e r o in a n d m e t h a d o n e : Deficient growth SIDS Withdrawal symptoms Premature birth
Study on cocaine and tobacco useNess et al., 1999
A large inner city sample n = 400, miscarriages n = 570, no miscarriage Adjusted for demographics and other drug use
Findings: S e l f -r e p o r t e d c o c a in e u s e : neither
drug was significantly related to miscarriage A c t u a l u s e w a s d e t e r m in e d b y
a n a ly s is o f u r in e a n d h a ir s a m p le s : both drugs were significantly related to miscarriage Cocaine increased probability of miscarriage 1.4
times Smoking increases probability of miscarriage 1.8
times
Cocaine “crack” babies of the 1990s
Child born to mother who used crack-cocaine during pregnancy
Once written off as “lost generation” Susceptible to prenatal stroke,
irreversible brain damage, or a heart attack
Withdrawal symptoms at birth Increased risk of mental
retardation and cerebral palsy Deficits in information-
processing, and attention to tasks
The Parent Child Intervention Program was established specifically to help prenatally drug-exposed youngsters. Teachers try to provide a carefully monitored and highly structured environment for the students.
Crack babies are now seen as 1990s myth because adopted babies do well
It was the post-natal environment, combined with prenatal vulnerability, that led to learning disabilities and ADHD in cocaine-exposed children
Addendum: Theorists working in new or unexplored domains often borrow ideas from well understood domains
E x a mp l e : T h e s o la r s y s t e m m a y h a v e s e r v e d a s t h e s o u r c e
D o m a in f o r N e i l B o h r ' s m o d e l o f t h e a t o m .
S o u r c e d o m a in : S o la r s y s t e m ' s p la n e t s a r e k e p t c ir c l in g a r o u n d t h e s u n b y g r a v it a t io n a l f o r c e s
T a r g e t d o m a in : e le c t r o n s c i r c le t h e m a s s f o r m e d b y p r o t o n s a n d n e u t r o n s
Characteristics of the Stages of Organogenesis
N o t u r n in g b a c k : T im e ( v ia a m a t u r a t io n a l
c lo c k ) d r iv e s t h e s t a g e s O r g a n s c a n o n ly
d i f f e r e n t ia t e d u r in g a c e r t a in p e r io d
N o s e c o n d c h a n c e s D e v e lo p m e n t p r o c e e d s v ia : In c r e a s in g d i f f e r e n t ia t io n
o f s t r u c t u r e s In c r e a s in g in t e g r a t io n o f
s t r u c t u r e s
Prenatal development: “No turningback…
F r e u d b o r r o w e d " n o t u r n in g b a c k , n o s e c o n d c h a n c e s " f r o m s t u d ie s o f m a m m a l ia n p r e n a t a l d e v e lo p m e n t w h e n h e f o r m u la t e d h is t h e o r y o f h u m a n p e r s o n a l i t y d e v e lo p m e n t .