Flashcards in LEC49: Late Fetal Period & Twins Deck (66):
fragment of time OBGYNs measure trimesters by
weeks, not months
1st trimester time pd
2nd trimester time pd
3rd trimester time pd
what occurs during 1st trimester
major organ systems form
what occurs during 2nd trimester
fetal growth, differentiation- organ systems develop ability to take on roles, fxns as they should in a born baby
allows to visualize fetus, see anomalies
when is fetus viable
24 weeks from LMP, end of 2nd trimester
when is fetus peri-viable?
what occurs during 3rd trimester
continued growth, maturation, development of embryo
why is it important to accurate date pregnancy?
many things occur at very specific times during pregnancy so must know accurately how old fetus is
when can visualize fetal heart beat on U/S?
6 weeks from LMP, 4 weeks since conception
what are carnegie stages?
why to visualize embryonic pd of fetal development - til 8 weeks, 10 weeks from LMP
visualize by morpholgy, not just by age
crown-rump length: measure from crown of head to rump- accurate for dating fetus within 3-5 days
when can use CRL?
weeks 9-12 features
1) head = 1/2 CRL of fetus
2) eyes fused
3) ears low
4) see some ossification cts appear in skeleton
when do primary ossification cts appear?
end of 12th week
weeks 13-16 highlights
1) coordinated limb movements
2) ossification of skeleton active
3) scalp hair patterning determined
4) genetalia recognizable
5) eyes anterior
17-20 week highlights
1) mother feels movement
2) skin covered w/ vernix
3) fine lanugo hair present
4) brown fat forms- heat production
5) anatomy US routinely performed
what is vernix
waxy white protection over skin
appears weeks 17-20
why might baby at 24 weeks have trouble w/ heat production
brown fat hasn't formed
when is uterus at level of umbilicus/bellybutton?
20 weeks since LMP
1 cm from pubic symphysis=1 week
21-24 weeks features
1) skin wrinkled, translucent
2) beginning of surfactant production
3) viability est
26-29 weeks features
1) lungs more developed
2) CNS can control rhythmic breathing, body temp
3) eyelids open at 26 weeks
4) subcutaneous fat
30-34 weeks features
1) skin pink, smooth
2) 32 weeks decreased risk of bleed in brain
3) majority survive
when do eyelids open
when is preterm
< 27 weeks
when is early term
when is full term
when is post term
biggest risk factor for having a preterm birth?
if mom has prior hx of having preterm birth
all risk factors for preterm birth?
1) prior preterm birth
2) uterine anomaly
3) multiple gestation
4) excess amniotic fluid
5) cigarettes/drug use
6) intrauterine infection
how to treat woman who has had prior preterm birth?
diabetes effect on fetal growth?
if mom has diabetes, excess sugar stimulates fetus to create growth factor; can get fetus that's TOO BIG or too SMALL
what factors might restrict fetal growth?
1) vascular disease
4) genetic disorders
5) anti-phospholipid antibody syndrome
possible post-term issues?
1) increase in mortality
2) dry parchment-like skin, long nails, decreased vernix
3) meconium aspiration
spontaneous incidence of multiple gestations in US?
why increase in multiple births nationwide?
use of ART, increase in maternal age
what are dizygotic twins
twins from 2 diff eggs; each forms own amnion, chorion
which type of twinning is familiar
percentage of twins that're dizygotic
is dizogytic twins maternal or paternal inheritance
what is monozygotic twins
1 embryo that splits
if 4-8 day split, 1 placenta w/ 2 sacs
if 8-13 day split, 1 sac - risk for fetal death
when do conjoined twins occur
after day 13, monozygotic twins
is monozygotic twins inherited
which has better outcome- dizogytic or or monozogytic twins
hw might monozygotic twins present
2 separate amnions; 1 placenta w/ 2 diff sacs OR if split before day 4, 2 placentas w/ 2 sacs
day 3-5 twin type
day 5-8 twin type
day 8-13 twin type
day 13+ twin type
what are monochorionic twins risk for?
1) fetal growth restriction
2) twin-twin transfusion syndrome
3) congenital anomalies
5) preterm birth
degree of risk, least to greatest, re: twin type?
di and mono
complications of multiple births for baby?
1) preterm brith
2) low birth weight
3) neonatal morbidity and morality
4) congenital anomalies
5) chromosomal abnormalities
6) spontaneous fetal loss
complications of multiple births for mom?
1) gestational diabetes
3) cesarean delivery
4) maternal hemorrhage
5) acute fatty liver
6) placenta previa
when did rate of twins peak in USA
when do singletons deliver
when do twins deliver
when do triplets deliver
when do quads deliver
what delivers earlier- multiple births or singleton?
complications of prematurity
2) patent ductus arteriosus
3) intracranial hemorrhage
5) respiratory abnormalities
6) necrotizing enterocolitis
8) retinopathy of prematurity
9) learning disabilities, developmental delays, cerebral palsy
risk of CP in multiple birth?
twins: 5x increased risk
triplets: 17x increased risk
what factors increase perinatal morbidity, mortality?
fetal growth restriction and discordant growth
why do dizygotic twins have great risk of chromosomal anomalies?
each twin has independent risk, whereas monozygotic twins have genetically identical risk
so 2x age related risk for dz twins