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
teratogens
env. agent that produces developmental deviation or termination of pregnancy
critical periods
organs most vulnerable during embryonic stage but each have different critical periods
dose response principle
higher-dose = more severe damage
teratogen examples
x-rays, pesticides, viruses, caffeine, drug use, OTC meds, alcohol
alcohol during pregnancy
~80% drink @ some point in pregnancy
- > 3 drinks/day associated w/miscarriage and birt defects
Fetal alcohol syndrome
affects facial features, 1/750 infants and up to 6% born to alcoholic mothers
Fetal alcohol effects
FAE, even if mothers consume small amounts of alcohol
immediate effects of alcohol
- LBW
- premature birth
- microcephaly/ face morphology
- joint defects
- heart defects
- CNS dysfunction
- irritable
long term effects of alcohol
- mental retardation
- learning disabilities
- hyperactivity
- seizure disorders
- greater risk for alcohol related problems during adulthood
smoking during pregnancy, teratogenic responses
reduces O2 and increases CO in mother’s blood
- increases miscarriage
- LBW, premature birth
- SIDS
- heart problems, breathing difficulty
smoking during pregnancy sleeper effects
LDs or mental retardation
- ADHD, hyperactivity, behavior disorders
- respiratory problems
- obesity, shorter stature
- substance abuse
teratogen principles
- timing is important
- dosage matters
- individual variations
- both parents’ health matters
- teratogens interact in unexpected ways
- some drugs important for mothers health but effect is unknown
innate vulnerability to teratogens
some zygotes carry genes that make them vulnerable, generally male fetuses more vulnerable
maternal prenatal influence factors
diet/exercise -> vitamins, low-impact regular exercise, maternal obesity, malnutrition
- increased risk w/older and younger age
- prenatal support
- maternal stress -> slower growth rate, LBW, temperamental difficulties
- health
father prenatal influence
less research
- substance use
- second-hand smoke
- father’s treatment of mother
labor process begins
contractions, release of corticotropin-releasing hormone (oxytocin)
possible hazards during labor
anoxia - lack of oxygen, can occur slowing fetal heart rate, if too long = brain damage, risk for cerebral palsy
medications during labor
pitocin - can speed up labor and contractions
epidural - pain relief, injection/lube in lower block, longer labor chances
apgar scale
assessment of newborn’s heart rate, done twice (1 min and five min after birth)
- score of 0-2 in each score, desired score = 7+
pre-term infants
born before 37 weeks, after week 25 survival rate of 50%
low birth-weight infants
less then 5.5 lbs, increased vulnerability to infection risk for respiratory distress syndrome (RDS)
–> approx 8% in US, 20% worldwide
very LBW infants
less then 1250 g (2.25 lbs) OR < 30 weeks
- 1.4% all live births US
small for gestational age infants
- weight <90% of average weight of infants of same gestational age
compared to normal BW, LBW at risk for:
- physical health difficulties
- respiratory difficulties
- eye disorders
- cerebral palsy, seizure disorders, neurological difficulties
- cognitive challenges
- behavior problems/social skill deficit
- abuse
causes of LBW
teratogens, air pollution, multiple births
- mother’s behavior
- father’s behavior
outcomes for LBW infants
postnatal env. can effect outcomes
- maternal support, responsive and stimulating care
- more problems for economically disadvantaged
- medical costs 3-20x higher
- many end up with minimal problems, by 18-22 months, 16% of VLBW infants unimpaired and only 22% mildly impaired
immigrant paradox
recent immigrants (more likely to have SES/education) have babies healthier/heavier babies than US counterparts
Cesarean (c-section) delivery
baby surgically removed uterus
c section occurs most
fetal distress, breech, transverse (cross-wise), baby too large, previous c-section, older mothers
c-section = controversial why?
requires anesthesia, longer recovery, greater risk for maternal infection, no difference in quality of mother-child interactions after 1 year
infant mortality rates
death before age 1
- declined since 1960s but US rates still high
- african americans with highest, lowest among asians
newborn reflexes
- maintaining O2 - breathing, hiccupping, sneezing
- maintaining constant body temp - crying, sivering, tucking legs to body, pushing
- managing feeding - sucking, rooting, swallowing
reflexes not necessary for survival but signify state of brain and body functions
babinski, stepping, palmar grasping, moro
