Discontinuation of Oxytocin in the Second Stage of Labor and its Association with Postpartum Hemorrhage

Abstract

Objective: To evaluate whether patients with oxytocin discontinued during second stage of labor (≥ 30 minutes prior to delivery) had lower rate of postpartum hemorrhage (PPH) compared to those with oxytocin was continued until delivery or discontinued < 30 minutes prior to delivery. Study Design: Retrospective cohort study performed from 8/1/14-7/31/19. Singleton pregnancies 24-42 weeks gestation were included if they reached second stage of labor and received oxytocin during labor. Patients on anticoagulants were excluded. Patients with oxytocin discontinued ≥ 30 minutes prior to delivery represented STOPPED and those that did not comprised CONTINUED. Patient data were abstracted from electronic medical record. Primary outcome was PPH (≥ 1000 mL blood loss). Univariable analyses were performed to compare groups. Multi-variable logistic regression was performed to adjust for prespecified confounders. Planned sub-group analyses by route of delivery were performed. Results: Of 10,421 total patients, 1,288 had oxytocin STOPPED and 9,133 had oxytocin CONTINUED. There were no significant differences in age, race, or ethnicity, BMI, public insurance, gestational diabetes, or pregnancy induced hypertension between STOPPED and CONTINUED. PPH rate was 15.2% and 5.7% in STOPPED and CONTINUED, respectively (p < 0.001). After adjusting for confounders, STOPPED remained at higher odds for PPH (aOR 2.859, 95% CI 2.394, 3.414, p <0.001). Among cesarean deliveries only there was no significant difference in rate of PPH between STOPPED and CONTINUED (38.0% vs 36.4%, respectively, p=0.730). However, among vaginal deliveries, rate of PPH was actually lower in STOPPED than CONTINUED (3.4% vs 5.2%, respectively, p = 0.024). Conclusion: The rate of PPH was higher in patients with oxytocin STOPPED compared to CONTINUED. However, among vaginal deliveries there was a significantly lower rate of PPH in STOPPED. These disparate findings may be explained by variable impact of second stage oxytocin on PPH as a function of delivery type.