Association of Oxytocin Rest During Labor Induction of Nulliparous Women With Mode of Delivery.

Objective: To evaluate the association between temporary cessation in oxytocin infusion (oxytocin rest) and mode of delivery in women undergoing induction of labor with a protracted latent phase.

Methods: We conducted a retrospective cohort analysis of nulliparous women with term, vertex, singleton gestations who were undergoing induction of labor with continuous oxytocin infusion at a large academic medical center. Episodes of oxytocin rest were identified among patients who were exposed to 8 hours of continuous oxytocin yet remained in latent labor (ie, protracted latent labor). Multivariable logistic regression analysis was performed to estimate the association between duration of oxytocin rest and mode of delivery while adjusting for duration of latent phase, maternal age, gestational age, body mass index, and indications for induction and oxytocin cessation. Maternal and neonatal morbidities were also compared among patients with different durations of oxytocin rest.

Results: From January 2012 to December 2016, 1,193 patients met eligibility criteria. Among these patients, 267 patients (22.4%) underwent an oxytocin rest that lasted at least 1 hour. After adjusting for potential confounders, the odds ratios of cesarean delivery for patients with oxytocin rest compared with those with no oxytocin rest were as follows: 1.12 (95% CI 0.79-1.58) for less than 1 hour, 0.78 (95% CI 0.48-1.27) for 1-2 hours, 0.60 (95% CI 0.35-1.04) for 2-8 hours, and 0.43 (95% CI 0.24-0.79) for 8 hours or more. We did not detect an association between oxytocin rest of more than 8 hours and a composite of maternal or neonatal morbidities.

Conclusion: An oxytocin rest of at least 8 hours is a clinical tool that may reduce the risk of cesarean delivery among women with protracted latent labor without significantly increasing maternal or neonatal morbidity.