Induction of labor in twin pregnancies - A retrospective cohort study

To investigate outcomes in spontaneous and induced twin deliveries. Secondary aims were to study impact of delivery interval and breech presentation of the first twin.

This retrospective cohort study comprised 354 twin deliveries at a tertiary Norwegian hospital. Spontaneous labor onset and induction of labor were compared in women with planned vaginal delivery and gestational age ≥ 34 weeks. The main outcome was intrapartum cesarean section. Secondary outcomes were umbilical arterial pH and five-minute Apgar scores.

Among the induced labors, 63/229 (27.5%) women underwent intrapartum cesarean section, compared to 45/125 (36%) in spontaneous labors (P = 0.10). Odds ratio for intrapartum cesarean section in induced labors was 0.65 (95% CI 0.40-1.04) after adjusting for maternal age and parity. Median umbilical arterial pH was significantly lower in the second twins in both spontaneous and induced labors, 7.28 (6.94-7.43) vs. 7.32 (7.16-7.42), and 7.27 (6.90-7.48) vs. 7.29 (7.08-7.45), respectively. pH < 7.00 rarely occurred. Second twins born after a delivery interval > 30 min had a significantly higher frequency of pH < 7.10 than those with a shorter interval, P < 0.01. No significant difference was found in frequency of pH < 7.10 between breech-presenting and cephalic-presenting first twins (P = 0.65). One unexpected intrapartum fetal death occurred after labor induction.

Our results support spontaneous onset and induction of labor as safe. Intrapartum cesarean section rates did not differ significantly between spontaneous and induced labors. Delivery interval > 30 min was associated with a lower pH in the second twin.