Objective: To evaluate whether adding oxytocin to preinduction cervical ripening with a Foley catheter increases the rate of delivery within 24 hours.
Methods: This was a randomized, multicenter, parallel trial of women with a singleton pregnancy at 24 weeks of gestation or greater undergoing labor induction. Women were randomly allocated to an intracervical Foley catheter followed by oxytocin or Foley with concurrent oxytocin infusion. Nulliparous and multiparous women were randomized and analyzed separately based on parallel design. The primary outcome was Foley placement to delivery at 24 hours or less. A sample size of 100 nulliparous women and 75 multiparous women per group would be required to detect a 20% increase in baseline 24-hour delivery rate with 80% power for each parity group.
Results: From January 2015 through July 2016, 323 patients were enrolled: 184 nulliparous women and 139 multiparous women. Nulliparous women who received concurrent Foley and oxytocin delivered more frequently within 24 hours of Foley placement than did the Foley followed by oxytocin group (64% compared with 43%, P=.003, relative risk 1.51, 95% confidence interval [CI] 1.14-2.00). Multiparous women who received concurrent Foley and oxytocin delivered more frequently within 24 hours than the Foley followed by oxytocin group (87% compared with 72%, relative risk 1.22, 95% CI 1.02-1.45). Median time to delivery was shorter in both nulliparous women (20.9 compared with 26.1 hours, P<.001) and in multiparous women, (14.9 compared with 18.6 hours, P=.01) who received concurrent Foley and oxytocin compared with Foley followed by oxytocin. There were no significant differences in the rates of cesarean delivery, postpartum hemorrhage, chorioamnionitis, or neonatal intensive care unit admission between the randomization groups.
Conclusion: Induction with concurrent oxytocin infusion added to Foley significantly increases the rate of delivery within 24 hours in both nulliparous and multiparous compared with Foley followed by oxytocin.
Clinical trial registration: ClinicalTrials.gov, https://clinicaltrials.gov/, NCT02273115.