Perinatal Outcomes of Twin Pregnancies in Women with Unicornuate Uterus

Background: It is known that unicornuate uterus is a type of Müllerian anomalies and is associated with adverse pregnancy outcomes. However, previous studies on unicornuate uterus were mostly on singleton pregnancies, the perinatal outcomes of twin pregnancies with unicornuate uterus remains elucidating.This research aimed to investigate the perinatal outcomes of twin pregnancies in women with unicornuate uterus. Methods: A total of 283 women with unicornuate uterus, 21 twin pregnancies (group A), 262 singleton pregnancies (group B) and 105 twin pregnancies with normal uterus (group C) were enrolled who delivered at West China Second University Hospital, Sichuan University from January 2013 to December 2022, general characteristics and perinatal outcomes were retrospectively analyzed. Results: In twenty-one twins with unicornuate uterus, 20 cases (95.2%) were dichorionic diamniotic twins and 1 case (4.8%) monochorionic diamniotic twin. Seventeen cases (81.0%) were conceived by in vitro fertilization-embryo transfer (IVF-ET) and 4 cases (19.0%) naturally. The mean gestational weeks of delivery were (33.8±5.7) weeks and 19 cases (90.5%) were cesarean section.The twin group (A) was associated with a significantly higher rate of preterm premature rupture of membranes (38.1%,8/21), preterm deliveries (85.7%,18/21) (preterm delivery (PTD) was defined as a birth occurring after 28 weeks and before 37 completed weeks of gestational age), and neonatal intensive care unit (64.3%,27/42) than that of group B and group C ( p <0.05). Moreover, the live birth weight in group A (1931.7±535.2)g was lower than in group B and group C ( p <0.001). Conclusions: The incidence of complications and risk of adverse perinatal outcomes in twin pregnancies with unicornuate uterus is higher than that in singleton with unicornuate uterine and twin pregnancies with normal uterine. Thus, maternal and fetal monitoring during pregnancy should be strengthened to achieve good outcomes.