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Updated: Jul 7, 2026

Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas
Published on: September 5, 2011
Twin chorionicity and the risk of stillbirth
Young Mi Lee1, Blair J Wylie, Lynn L Simpson
1Division of Maternal Fetal Medicine, Department of Obstetrics & Gynecology, Columbia University Medical Center, New York, New York 10032, USA. yml9002@med.cornell.edu
Objective:
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.
Level Of Evidence:
II.
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