Continuous versus Intermittent Induction of Labor with Oxytocin in Nulliparous Patients: A Randomised Controlled Trial

Oxytocin is considered the drug of choice for labor induction, although the optimal protocol and infusion duration remain to be determined.To assess whether Oxytocin infusion duration increases 24-hour delivery rates and affects time to delivery length and patient's experience.A randomized controlled trial was performed at a single tertiary medical center, between January 1, 2020 and June 30, 2022. Nulliparous patients, with a singleton pregnancy at a vertex presentation and a Bishop score ≥ 6 were randomly assigned to receive either continuous (16 h, with a 4 h pause in between infusions) or intermittent (8 h, with a 4 h pause in between infusions) Oxytocin infusion, until delivery. In both groups infusion was halted on signs of maternal or fetal compromise. Randomization was conducted with a computer randomization sequence generation program. The primary outcome was delivery within 24 h from the first Oxytocin infusion and the secondary outcome included time-to-delivery, mode of delivery, and additional maternal and neonatal outcomes. Seventy-two patients per group were to be randomized to reach 80% power with a 20% difference in the primary outcome according to previous studies.A total of 153 patients were randomized, 72 to the continuous Oxytocin infusion group and 81 to the intermittent infusion group. The total Oxytocin infusion time was similar between the groups. Patients in the continuous arm were more likely to deliver within 24 h from Oxytocin initiation (79.73% vs. 62.96%, p<0.05), and had a shorter Oxytocin-to-delivery time interval, compared with patients receiving intermittent treatment (9.3±3.7 h vs. 21±11.7 h, p<0.001). Furthermore, time from ruptured membranes to delivery was shorter (9.3 ± 3.7 h vs. 21 ± 11.7 h, p<0.0001) and chorioamnionitis was less frequent (9.46% vs. 21%, p<0.05) in the continuous compared with the intermittent arm. Cesarean delivery rate was 20% in both groups (p=0.226). There was no difference in post-partum hemorrhage, or adverse neonatal outcomes between the groups. Patients receiving continuous Oxytocin infusion were more satisfied with the birthing experience.Continuous infusion of Oxytocin for labor induction in nulliparous patients with a favorable cervix may be superior over intermittent Oxytocin infusion, since it shortens time-to delivery, decreases chorioamnionitis rate and improves maternal satisfaction, without affecting adverse maternal or neonatal outcomes.