946: Mode of delivery and the risk of adverse outcomes in preterm twins < 28 weeks

Objectives To determine the association between mode of delivery in extremely preterm twins born Methods A retrospective cohort study of live-born twin infants born between 24+0 and 27+6 weeks of gestation, and admitted to level III neonatal intensive care units participating in the Canadian Neonatal Network between 2010–2017. Neonatal outcomes of Vx/NonVx twin gestations in which the first twin was born vaginally (Vx/NonVx-VD group, reflecting a definite trial of vaginal birth, with the second twin born either vaginally or via cesarean section (CS)) were compared with outcomes of Vx/NonVx twins where both twins were born via cesarean section (Vx/NonVx-CS group). In addition, given that we were unable to rule out a trial of labor in the Vx/NonVx-CS group prior to the CS, we included a second group of twins born via CS due to non-vertex presentation of the presenting twin (NonVx-CS group) where a trial of labor could not have been taken. The primary outcome was a composite neonatal outcome defined as neonatal death, severe neurological injury or birth trauma. Results A total of 390 women with a twin gestation (780 twin infants) were included in the analysis. Of those, 112 were in the Vx/NonVx-VD group, 108 in the Vx/NonVx-CS group, and 170 in the NonVx-CS group. The risk of the primary outcome in the trial of vaginal delivery (Vx/NonVX-VD) group (42%) did not differ significantly from the Vx/NonVx-CS group (37%, aRR=0.93, 95% CI 0.71–1.22) and from the NonVx-CS group (34%, aRR=1.20, 95% CI 0.92–1.58). The risk of secondary outcomes was also not different between the groups. Findings remained unchanged when the results were analyzed separately for the presenting and non-presenting twin. Conclusions In extremely preterm twins born at