High- vs low-dose oxytocin in lean and obese women: a double-blinded randomized controlled trial

BACKGROUND: Women with obesity are likely to experience longer lengths of labor and are at an increased risk of cesarean delivery. We hypothesized that high-dose oxytocin would decrease the time to delivery in a cohort of women with obesity undergoing induction of labor. OBJECTIVE: This study aimed to assess whether women with obesity benefited from higher doses of oxytocin for induction of labor. STUDY DESIGN: A double- blinded randomized controlled trial was conducted to evaluate the effect of low-dose and high-dose oxytocin on length of labor. We recruited women who were undergoing induction of labor at >= 37 weeks of gestation. Patients were randomly assigned in a 1:1 ratio to receive low-dose or high-dose oxytocin stratified by obesity level (obese and lean). The primary outcome was length of time (minutes) to vaginal delivery. The secondary outcomes included overall cesarean delivery rate, cesarean delivery for labor arrest, maximum oxytocin infusion rate, oxytocin infusion discontinuation, oxytocin infusion decrease, blood loss, neonatal intensive care unit admission, and neonatal Apgar scores. RESULTS: A total of 140 patients were randomized into receiving lowdose and high-dose oxytocin stratified into obese and lean stratum (35 for all strata). The primary outcome, time to vaginal delivery, was similar between the low-dose and high-dose oxytocin groups in the lean stratum 796 [+/- 411] vs 694 [+/- 466] minutes; P=.363) and the stratum with obesity (715 [+/- 497] vs 762 [+/- 594] minutes; P=.733). Kaplan-Meier curves between the low-dose and high-dose oxytocin groups were not significantly different in the lean stratum (P=.391) and the stratum with obesity (P=.692). There were 5 cesarean deliveries (14.29%) in the low-dose oxytocin lean stratum vs 2 cesarean deliveries (5.71%) in the high-dose oxytocin lean stratum (P=.232). There were 4 cesarean deliveries (11.43%) in the low-dose oxytocin stratum with obesity vs 1 cesarean delivery (2.86%) in the high-dose oxytocin stratum with obesity (P=.164). There was no difference in the incidence of postpartum hemorrhage between the lean stratum (P=0.526) and the stratum with obesity (P=0.212). There was no difference in mean estimated blood loss between the lean stratum (P=.472) and the stratum with obesity (P=.215). CONCLUSION: There was no difference in time to delivery between the low-dose and high-dose oxytocin protocols in either the lean cohorts or cohorts with obesity undergoing induction of labor. We did observe a trend toward a lower rate of cesarean delivery in both lean women and women with obesity when high-dose oxytocin was used.