Prenatal Development Flashcards
Prenatal Development
development
of an organism from conception
through birth
Stages of Prenatal Development
Germinal Stage
Embryonic Stage
Fetal Stage: Week 9 to Birth
Germinal Stage
Cell differentiation and implantation occur
– CRITICAL POINTS:
• Hormonal changes make implantation optimal at 9
days, but unlikely AFTER 9 DAYS
• Upon implantation, embryo begins to take nutrients
from mother’s blood, and is now vulnerable to
TERATOGENS
– Excessive alcohol consumption especially dangerous
• Hormonal changes cause fatigue, nausea, and swollen
breasts
Embryonic Stage
Week 3 through 8: – Differentiation continues – CRITICAL PERIODS OF DEVELOPMENT: • Differentiation and growth occur rapidly • Essential structures form • Embryo is highly vulnerable to: – GENETIC ABNORMALITIES – ENVIRONMENTAL INFLUENCES THAT AFFECT CELL DIVISION AND/OR DAMAGE EMBRYO » Miscarriage (spontaneous abortion) » Brain damage, birth defects, etc. – Organogenesis; embryo is now a fetus
Fetal Stage: Week 9 to Birth
Period lasting approx 30 weeks of rapid growth and
development
– Weeks 9-12: sex organs develop
• Usually can be seen on ultrasound at 14 weeks, but not truly accurate
until 20 weeks
– Weeks 17-20: heartbeat can be heard
• Mother can feel movement
• About 5 inches long
– Week 24: rapid weight gain (“baby fat”)
• About 10 inches long
– CRITICAL POINT: Weeks 26 to 28
• Fetus is now viable if born premature due to mature lungs
• Fetus can turn head toward bright light outside womb
• Fetus sucks thumb, hiccups, and sleeps
– Weeks 28 to 40:
• Rapid weight gain (5 lbs)
• All organ systems become fully formed
• Brain develops rapidly
Chances of getting pregnant
– 20-24 years: 20% probability with unprotected sex
– 30 years: 15%
– 35 years: <10%
Infertility
– Approx. 1/3 attributed to fertility problem in female
– Approx. 1/3 attributed to fertility problem in male
– Approx. 1/3 attributed attributed to both or unexplained
Factors that compromise sperm health
– Age – Workplace toxins – Tobacco (smoking and chewing) – Alcohol, Illicit drugs – Heat – Stress – Other factors that may reduce production or quality of sperm
Factors affecting ova and ovulation
– Ovulation Disorders – Fallopian tube damage (e.g, STD’s, ectopic pregnancy) – Endometriosis – Stress – Illness – Toxins – Tobacco, alcohol, drug use, caffeine – Weight: unhealthy BMI – AGE
TERATOGENS
Environmental factors that can cause
birth defects
Example: Thalidimide •Drug used to treat nausea in pregnant women in the 1950’s and 60’s •Causes shortening of limbs; “Flipper-like” arms
Critical Periods
• Vulnerability of fetus to teratogens varies throughout pregnancy – Germinal stage: lower risk • No nutrient sharing • Exposure likely fatal – Embryonic stage: highest risk • Nutrient sharing during organogenesis • Exposure =major malformations/damage – Fetal stage: moderate risk • Exposure unlikely to be fatal • Can cause malformation and mental retardation
Alcohol
Alcohol crosses placenta, disrupts cell division, and
kills fetal cells
• Reduces blood flow through placenta to fetus
• Exposure during pregnancy can cause:
– Damage to brain/central nervous system
– Physical deformities
– Growth retardation
– Miscarriage/death
– FETAL ALCOHOL SYNDROME
– Inattention, impulsivity, learning problems
FETAL ALCOHOL SYNDROME
FAS
Growth deficiency • Head and facial deformities • Dysfunction of CNS – Mental retardation – Poor motor fx: Cerebral palsy – Inattention, impulsivity, poor executive functioning
How much alcohol is too much
• FAS usually occurs when mother is:
– Chronic alcoholic (6 or more drinks per day)
– Binge drinker (4+ drinks at one time/1x per wk)
• Some studies suggest one drink per week can result in
Inattention, hyperactivity, and increased aggression
– One episode of binge drinking can cause brain damage
• Best practice: abstinence during pregnancy
– Even when trying to conceive!
Cocaine
prematurity, growth retardation,
malformation in brain, intestines, genitals,
etc., impaired sensory fx, increased arousal,
decreased autoregulation, higher risk of LD,
ADHD, language problems
