Mode of Delivery in Monochorionic Compared With Dichorionic Twin Pregnancies.

Objective To compare mode of delivery between monochorionic and dichorionic twin pregnancies. Methods This was a retrospective cohort study of women undergoing delivery of diamniotic twins in a single maternal-fetal medicine practice in New York City between 2005 and 2021. We compared baseline characteristics and delivery outcomes between monochorionic and dichorionic gestations. The primary outcome was mode of delivery. For monochorionic-diamniotic twin pregnancies at or after 34 weeks of gestation, we also compared neonatal outcomes between women who did and did not attempt vaginal delivery. Data were analyzed using the χ2 test, Fisher exact test, and t test when appropriate. Results A total of 1,121 diamniotic twin pregnancies were identified, of which 202 (18%) were monochorionic and 919 (82%) were dichorionic. Mode of delivery did not differ between monochorionic and dichorionic pregnancies, both in the overall cohort (cesarean delivery rate 61% vs 63%, P=.54) and in the subgroup of women who attempted vaginal delivery (cesarean delivery rate 22% vs 21%, P=.80). For patients with a vaginal delivery of twin A, the mode of delivery for twin B did not differ between the groups. Among the patients with monochorionic pregnancies at or after 34 weeks of gestation, neonatal outcomes did not differ between women who did and did not attempt vaginal delivery. Conclusion Monochorionic-diamniotic pregnancies are not at an increased risk of cesarean delivery when compared with their dichorionic-diamniotic counterparts.