Vaginal dinoprostone vs Foley catheter for induction of labor at term with an unfavorable cervix: an open-label randomized controlled trial

Background: Induction of labor (IOL) with mechanical methods or pharmacological agents is used in about 20% to 30% of all pregnant women. We specialized in comparing the effectiveness and safety of dinoprostone vs transcervical Foley catheter for IOL in term pregnant women with an unfavorable cervix with adequate samples. Objective: To compare the effectiveness and safety of dinoprostone vs transcervical Foley catheter for IOL in term pregnant women with an unfavorable cervix. Study Design: This is a parallel, open-label randomized controlled trial in two maternal centers in Shanghai, China between October 2019 and July 2022. Women with a singleton pregnancy in cephalic presentation at term and an unfavorable cervix (Bishop score <6) scheduled for IOL were eligible. A total of 1860 women were randomly allocated to cervical ripening with either a dinoprostone vaginal insert (10 mg) or a 60 cc Foley catheter for up to 24 hours. The primary outcomes were vaginal delivery rate and time to vaginal delivery. Secondary outcomes included time to delivery and maternal and neonatal morbidity. Analysis was done from an intention-to-treat perspective. The trial was registered with the China trial registry (CTR2000038435). Results: The vaginal birth rates were 72.8% (677/930) vs 69.9% (650/930) in vaginal dinoprostone and Foley catheter, respectively (aRR 1.04, 95% confidence interval [CI] 0.98-1.10, risk difference: 0.03). Time to vaginal delivery was not significantly different between the two groups (sub-distribution hazard ratio 1.11, 95% CI 0.99-1.24). Vaginal dinoprostone was more likely complicated with hyperstimulation with fetal heart rate changes (5.8% vs 2.8%, aRR 2.09, 95% CI 1.32-3.31) and placenta abruption (0.9% vs 0.1%, aRR: 8.04, 95% CI 1.01-64.15), while Foley catheter was more likely complicated with suspected intrapartum infection (5.1% vs 8.2%, aRR: 0.62, 95% CI 0.44-0.88) and postpartum infection (1.4% vs 3.7%, aRR: 0.38, 95% CI 0.20-0.72). The composite of poor neonatal outcomes was not significantly different between the two groups (4.5% vs 3.8%, aRR 1.21, 95% CI 0.78-1.88), while more neonatal asphyxia occurred in the dinoprostone group (1.2% vs 0.2%, aRR 5.39, 95% CI 1.22-23.92). In a subgroup analysis, vaginal dinoprostone decreased vaginal birth rate slightly in multiparous women (90.6% vs 97.0%, aRR 0.93, 95% CI 0.88-0.99). Conclusions: In term pregnant women with an unfavorable cervix, IOL with vaginal dinoprostone or Foley catheter has similar effectiveness. Foley catheter leads to better safety for neonates, while it may result in a higher risk of maternal infection. Furthermore, Foley catheter should be preferred in multiparous women.