Success rate of induction of labour in twin pregnancies relative to singleton pregnancies in a predominantly Chinese population.

Introduction: This study assessed the efficacy of induction of labour in twin pregnancies relative to singleton pregnancies within a predominantly Chinese patient population.

Methods: This retrospective case-matched cohort study included patients with twin pregnancies who underwent induction of labour at our institution in Hong Kong between 2012 and 2020. Patients with twin pregnancies were matched one-to-one with singleton pregnancies based on parity, maternal age, and the indication for induction of labour. The primary outcome was the mode of delivery. Secondary outcomes included the time from oxytocin infusion to delivery, indications for caesarean or instrumental delivery, and maternal and neonatal outcomes.

Results: In total, 160 women with twin pregnancies met the inclusion criteria and were matched with 160 singleton pregnancies. Caesarean section was performed in 42 patients (26.3%) with twin pregnancies and 27 patients (16.9%) with singleton pregnancies undergoing induction of labour. Patients with twin pregnancies had a significantly higher risk of caesarean section relative to those with singleton pregnancies (odds ratio=2.14, 95% confidence interval =1.14-4.04; P=0.024). Internal podalic version was required in 13.6% of cases for the vaginal delivery of the second twin. There was no significant difference between the groups in the time from oxytocin administration to vaginal delivery (P=0.143).

Conclusion: Despite a higher induction failure rate, about three quarters of twin pregnancy patients achieved successful vaginal deliveries. Our findings inform decision making for patients and obstetricians, emphasising the importance of training for internal podalic version to aid second twin delivery and reduce caesarean rates in twin pregnancies.