The worst of both worlds-combined deliveries in twin gestations: a subanalysis of the Twin Birth Study, a randomized,...

The reported incidence of combined twin delivery (vaginal delivery of twin A followed by cesarean delivery for twin B) ranges between 5% and 10%. These estimates are based mostly on small studies or retrospective data. We aimed to evaluate to incidence and risk factors for and outcomes of combined twin deliveries, using a subanalysis of the Twin Birth Study, a randomized, controlled, prospective study.

The Twin Birth Study included women with twin gestation between 32+0 and 38+6 weeks, with the first twin in vertex presentation at randomization. Women were randomized to planned cesarean delivery or planned vaginal delivery. For the purpose of this subanalysis, we included women who had a vaginal delivery of twin A. Women who had a combined delivery (cesarean delivery for twin B) were compared with women who had a vaginal delivery of both twins. Our primary objective was to identify risk factors for combined twin deliveries. Our secondary objective was to assess the rate of fetal/neonatal death or serious neonatal morbidity in combined deliveries.

Of the 2786 women included in the original study, 842 women delivered twin A by a vaginal delivery and were included in the current analysis, of whom 59 (7%) had a combined delivery. Women in the combined delivery group had a lower rate of nulliparity (22.0% vs 34.7%, P = 0.047) and higher rates of noncephalic presentation of twin B at delivery (61.0% vs 27.3%, P < 0.001) and spontaneous version from presentation at randomization of twin B (72.9% vs 44.3%, P < 0.0001). In a multivariable model, the only risk factor significantly associated with a combined delivery was transverse/oblique lie of twin B following delivery of twin A (adjusted odds ratio, 47.7; 95% confidence interval, 15.4-124.5). Twins B in the combined delivery group had a higher rate of fetal/neonatal death or serious neonatal morbidity (13.6% vs 2.3%, P < 0.001), 5-minute Apgar score <7, neonatal intensive care unit admission, abnormal level of consciousness, and assisted ventilation.

Transverse/oblique lie of twin B following vaginal delivery of twin A is a risk factor for combined delivery. Combined delivery is associated with higher risk of adverse neonatal outcomes of twin B. These data may be used to better counsel women with twin gestation who consider a trial of labor.