multiple gestations Flashcards
whats thought to have an impact on the increasing number of multiples?
- widespread use of assisted reproducvite technology and aging maternal population
Another term for chorionicity?
placentation
what does dichorionic refer to?
2 chorions produce 2 placentation sites
what is the least risky form of twinning?
dichorionic
dichorionic twinning accounts for what % of all natural twinning?
80%
what is monochorionic?
- development of one chorion results in a shared placental site
- places pregnancy at higher risk
monochorionic twinning accounts for what % of twin mortalities due to share vasculature?
50%
monoamniotic vs. diamniotic?
Monoamniotic: The development of a single amnion
Diamniotic: The presence of two amnions
what twin gestations have the highest incidence of mortality?
monoamniotic
why does monoamniotic twins have the highest risk of incidence of mortality?
because sharing the amniotic space increases risk for cord accidents
zygosity refers to?
- the number of zygotes produced at the time of fertilization
zygotic (Fraternal) twins occurs when?
- 2 seperate ova are fertilized by 2 seperate sperm cells
- not genetically identicle
what is the most common form of twinning?
- dizygotic (faternal) twins
zygotic gestations are always?
always dichorionic diamniotic and represent the least risky type of twinning because a placental site is not shared
what ensures dizygosity?
identifying different genders in a multifetal gestation
monozygotic or identical twins result when?
one ovum if fertilized by a single sperm
what is the least common form of twinning and the most risky?
monozygotic
the earlier the cleavage occurs the more that is shared T or F?
False
what occurs is cleavage occurs 13 days after conception?
conjoined twins
clinical signs of multiple gestations? (5)
- large for dates
- hyperemesis
- hypertension
- increased human chorionic gonadotropin
- increased alpha fetoprotein
premature labor is the most common complication of what?
multiple gestations because of increased uterine volume
Twin pregnancies are __X more likely than singleton pregnancies to be complicated by premature labor
5X
what is considered a significant finding associated with premature delivery?
cervical length of <2.5 cm or the presence of funneling
The birth weight of twins statistically averages ___% less than the birth weight of singletons of comparable gestational age?
10%
a fetal weight less than the 10th percentile is suggestive of?
IUGR
other signs of iUGR include?
- oligohydramnios
- high resistance umbillical artery pulsed doppler waveform
IUGR may be the result of?
twin-twin transfusion syndorme
The incidence of a major fetal anomaly in a multiple gestation is __% compared with ___% in a singleton pregnancy
The incidence of a major fetal anomaly in a multiple gestation is 4% compared with 2% in a singleton pregnancy
with multiples what % if there of a chance of having down syndrome?
4.6%
congenital anomalies associated with multiples?
- 4.6% risk of down syndrome
- major malformations
- anomalies affecting the central nervous system
- cerebral palsy
maternal complications associated with multiples?
- pregnancy- induced hypertension and preeclamsia are common
preeclampsia in a pregnancy with multiples presents?
- earlier and more severe then in singleton pregnancies
features of eclampsia include? (4)
- hypertension
- edema
- proteinuria
- convulsions