Maternal and Neonatal Outcomes in Twin Deliveries with Prolonged Second-Stage Duration of the Presenting Twin: a Retrospective Cohort Study.

To assess the risk of adverse maternal and neonatal outcomes as a function of the presenting twin second-stage duration. A retrospective cohort study of deliveries taking place in an academic medical center between 2005 and 2019. The study group included women with twin pregnancies with the first fetus in vertex presentation, who attempted vaginal delivery with epidural analgesia and attained the second stage of labor. Prolonged second stage (PSS) was defined as when exceeding the 95th percentile of presenting twin second-stage duration recorded among all parturients who achieved spontaneous vaginal deliveries in our center during the study period, stratified by parity: 3 h in nulliparas and 1 h in multiparas. Women with and without PSS were compared. The primary outcome was a composite of adverse maternal outcomes. A univariate analysis was conducted and followed by multivariate analysis. During the study period, 1,337 parturients (36% of twin deliveries) met study criteria, of these 22% (298) were nulliparous and 78% (1,039) were multiparous. The second stage of labor of the presenting twin was prolonged in 41 (13.8%) of the nulliparas and 64 (6.2%) multiparas. Prolonged second stage was associated with episiotomy, chorioamnionitis, endometritis, and blood product transfusion, as well as vacuum deliveries of the first and second twin, second-stage cesarean, and a higher rate of composite adverse maternal outcome in nulliparous (41.5% vs. 20.2%, p<0.01) and with higher rates of episiotomy, postpartum hemorrhage, and vacuum deliveries of the first and second twin, but a similar rate of composite adverse maternal outcome in multiparous women (7.8% vs. 9.3%, p=0.68); moreover, the composite adverse neonatal outcome was not increased in nulliparous (36.6% vs. 38.5%, p=0.81) nor in multiparous women (21.9% vs. 23.6%, p=0.75). Prolonged second stage of labor of the presenting twin was associated with an adverse composite maternal outcome in nulliparous and with postpartum hemorrhage in multiparous. Further larger studies are warranted to reinforce our findings.