222: Personalizing twin delivery management: A secondary analysis of a randomized clinical trial comparing planned caesarean or planned vaginal delivery

Abstract

We performed a secondary analysis of the Twin Birth Study (TBS) (ClinicalTrials.gov, NCT00187369) to evaluate whether there would be a differential benefit from planned CD, depending on maternal and pregnancy characteristics (baseline markers), and/or gestational age (GA) at delivery. The TBS is a multicenter, international, randomized trial comparing planned CD and planned VD in 2,800 women with a twin pregnancy with a cephalic-presenting first twin between 32 weeks 0 days and 38 weeks 6 days of gestation. Primary outcome for our secondary analysis was a composite adverse perinatal outcome (perinatal death or serious neonatal morbidity). Markers considered were maternal age, parity, history of previous CD, use of antenatal corticosteroids, estimated fetal weight (EFW) of the first twin, EFW of the second twin, >25% difference in EFW of the twins, presentation of twin B, chorionicity on ultrasound, method of conception, complications of pregnancy, ruptured membranes at randomization and GA at randomization. For each marker, we built a separate logistic regression model to model the composite outcome as a function of the specific marker, planned delivery mode, and marker-by-planned-delivery-mode-interaction. We further performed multivariable logistic regression with backward variable elimination separately in each trial arm. None of the studied baseline markers was associated with differential benefit from planned CD. GA at delivery was differentially associated with the outcome in the treatment arms (p for interaction 0.001). For GA 32+0- 36+6 weeks, VD was associated with fewer adverse outcomes compared to CD. For those born ≥ 37+0 weeks, 10 (1%) newborns suffered the composite perinatal outcome in the planned CD group versus 23 (2%) in the planned VD group (odds ratio 2.25; 95% confidence interval 1.06 to 4.77). The outcomes of neonates with the planned mode of delivery for twin pregnancies, with the first twin in cephalic position, differ depending on GA. From 32 to 37 weeks a planned VD seems favorable, while from around 37 weeks onwards, a CD might be safer. Since recent literature suggests earlier timing of delivery than was advised in the TBS, planned mode of delivery is still VD for twin pregnancies with the first twin in cephalic position.