J Obstet Gynecol. 2008 Feb;111(2):301-8.
Twin chorionicity and the risk of stillbirth.
Lee YM, Wylie BJ, Simpson LL, D'Alton ME.
Division of Maternal Fetal Medicine, Department of
Obstetrics and Gynecology, Columbia University Medical
Center, New York, New York.
Objectives:
To estimate the effect of chorionicity on the
risk of stillbirth in twins.
Methods:
A retrospective
cohort analysis was performed of all twin deliveries of
at least 24 weeks of gestation at a single tertiary care
center from December 2000 to May 2007. The risk of fetal
death with advancing gestation was calculated for
monochorionic-diamniotic twins and for
dichorionic-diamniotic twins. Overall in utero survival
was compared by using Kaplan-Meier analysis and a
hazards ratio with 95% confidence intervals estimated to
assess the degree of difference. Pregnancies affected by
growth abnormalities, anomalies, or twin-twin
transfusion syndrome were subsequently excluded and
survival by chorionicity similarly compared within these
"apparently normal" gestations.
Results:
Data from 1,000
consecutive twin pairs (196 monochorionic-diamniotic
twins and 804 dichorionic-diamniotic twins) were
analyzed. Stillbirths occurred in seven (3.6%)
monochorionic-diamniotic and nine (1.1%)
dichorionic-diamniotic twin pairs.
Monochorionic-diamniotic twins had a higher risk of
stillbirth compared with dichorionic-diamniotic twins,
both overall (log-rank P=.004) and at each gestational
age after 24 weeks, with this risk persisting in the
subset of 771 (130 monochorionic-diamniotic twins and
641 dichorionic-diamniotic twins) "apparently normal"
twins (log-rank P=.039).
Conclusion:
Monochorionicity
has a negative effect on the in utero survival of twins,
even among monochorionic-diamniotic twins without
abnormalities.
