Labor induction in twin pregnancies: Does the perinatal outcome differ according to chorionicity?

To compare perinatal outcomes following induction of labor in dichorionic versus monochorionic twin pregnancies.

A retrospective cohort study analyzing all women with twin pregnancies who underwent induction of labor in a single university-affiliated tertiary medical center. The cohort included 290 women who were divided into 2 groups according to chorionicity: (1) dichorionic twin pregnancies (n = 203); (2) monochorionic twin pregnancies (n = 87). Induction of labor methods included oxytocin infusion, extra-amniotic balloon catheter and artificial amniotomy. Primary outcome was defined as mode of delivery. Secondary outcomes included maternal and neonatal adverse events.

Primary outcome did not differ between groups, with vaginal delivery rate of 92.1% in the dichorionic group and 94.2% in the monochorionic group. Women with dichorionic twins delivered later compared to monochorionic twins (38.00 weeks vs. 36.43 weeks, respectively, p < 0.001). While no differences were observed in Apgar scores or umbilical cord pH measurements, dichorionic twins were less frequently admitted to the neonatal intensive care unit compared to monochorionic twins (2.4% vs. 3.4%, p = 0.01 for 1st twin; and 6.9% vs. 10.3%, p = 0.089 for 2nd twin). Multivariate logistic regression adjusting outcomes to potential confounders, found gestational age at delivery to be the only variable significantly associated with neonatal intensive care unit admission rates (odds ratio 0.236, 95% confidence interval 0.152-0.366, p < 0.001).

Labor induction might be considered for both di- and monochorionic uncomplicated twin pregnancies with excellent vaginal delivery rates. The higher rates of neonatal adverse outcomes among monochorionic twins are presumably related to earlier gestation age at delivery.