prenatal dev and birth Flashcards
stages of prenatal development
germinal, embryonic, fetal
germinal stage
fertilization - 2 weeks
zygote divides and forms blastocyst that travels to fallopian tubes and implants in uterus, pregnancy detectable in mother’s urine
what happens to cells during germinal stage
methodical cell division and cell specialization begins
ectopic pregnancies
- egg implanted outside of uterus, often in fallopian tube
- embryo cannot survive and will cause pain and possible burst
- treated with medication or laparoscopic surgery
embryonic stage
3-8 weeks
- embryo attached to uterus
- major organ and basic anatomy development
during 3-4th week of embryonic stage
layers form: ectoderm, mesoderm, endoderm
- 1/4 inch long
organs/anatomy that develop during embryonic stage
neural tubes, neurons, heart (beats), ribs, muscles, GI tract, liver, pancreas etc
wks 5-8 of embryonic stage
- limbs, extremities
- umbilical cord/ placenta fully functional
- sex differentiation (week 7/8)
- 1 inch long, head 50% of body
- still gill/tail structure
fetal stage
9 wks - birth
- fetus
- 20x increase in length
- increase from 4oz (8 wks) to 7 lbs (birth)
first tri
up to wk 12
- rapid development
- heartbeat audible
- brain development
- genital formation
- 3 months, 3 oz, 3 in
second tri
- 13-24 wks
- movement felt by mother (16-20 wks)
- fetus responds to sound
- vernix and languo develop
- 14 inch, 2 lbs @ end
age of viability
babies born prior to 22 weeks
- don’t have respiratory system to survive
- 5% of all fetuses aborted spontaneously before 22 weeks
third tri
25-40 wks
- lungs fully develop
- 2/3 birth weight gained
- brain development accelerates
- sleep-wake cycle resembles newborn
avg newborn size
7.5 lbs, 20 inches
cephalocaudal
head to tail growth, head first then extremities
proximodistal
near to far, growth from center of body to extremities
vision development
24 weeks, fetus can see dim light through abdomen, helps set sleep schedule
touch and pain development
develops early in embryonic period, 20 wks fetus moves when abdomen touched
hearing development
sound level = 90 decibels, 25 wks fetus reacts to loud sounds, can recognize sounds
smell and taste
26 wks fetus can smell and taste through amniotic fluid
threats to development
nutrition, teratogens, mother’s emotional state/environment