(717) Low-dose versus high-dose oxytocin for induction and augmentation of labor: a randomized control trial.

To compare the effect of low-dose versus high-dose oxytocin regimens on time to delivery in nulliparous individuals undergoing induction or augmentation of labor.

Study Design:

Nulliparous individuals with singleton pregnancies at ≥ 37 weeks’ gestation who required oxytocin for induction or augmentation were randomized to receive a low-dose (2 milli-units/min initial dose, titrated by 2 milli-units/min every 20 minutes) or high-dose (6 milli-units/min initial dose, titrated by 6 milli-units/min every 20 minutes) regimen. Oxytocin was titrated to achieve adequate contractions; maximum rate of 40 milli-units/min. The primary outcome was time from oxytocin initiation to delivery. Secondary outcomes included mode of delivery, uterine tachysystole, and maternal and neonatal complications. Data were analyzed using Mann-Whitney Wilcoxon rank sum, Pearson chi-square tests, and a Kaplan-Meier curve with p< 0.05 considered significant. Sample size was calculated for superiority with a 25% difference rate and 80% power.

Results:
170 participants were randomized, 85 to the low-dose (with 1 withdrawal) and 85 to the high-dose group. Baseline characteristics were similar between groups. Most participants undergoing induction were admitted for elective labor and received mechanical cervical ripening with a Foley balloon. Median time from oxytocin initiation to delivery was 834 minutes in the low-dose group and 726 minutes in the high-dose group (p=0.26). Participants in the high-dose group received a higher maximum oxytocin dose (15.6 vs. 11.8 milli-units/min, p=0.004). No significant differences were found in mode of delivery or time to vaginal delivery (Figure 1, Table 1). The most common cesarean indications were failure to progress in the low-dose group and non-reassuring fetal heart rate in the high-dose group. Estimated blood loss was significantly higher in the high-dose group. No other significant differences were observed.

Conclusion:
High-dose oxytocin regimens did not significantly reduce time to delivery. While the high-dose group received higher maximum oxytocin doses, safety profiles were comparable.