A Quality-Improvement Study Evaluating Three Postpartum Prophylactic Oxytocin Rates and Blood Loss After Vaginal Birth

OBJECTIVE: To evaluate three rates of prophylactic oxytocin infusion after vaginal birth and blood loss. METHODS: We conducted a block-randomized quality-improvement initiative at an academic tertiary care center from June to October 2025. Patients with vaginal births were included. Three prophylactic oxytocin regimens were implemented in 2-week intervals: low infusion rate (83 mL/h; 10 international units over 2 hours), intermediate infusion rate (250 mL/h; 30 international units over 2 hours), and high infusion rate (500 mL/h; 30 international units over 1 hour). The primary outcome was median quantitative blood loss. Secondary outcomes included second-line uterotonic use, postpartum hemorrhage, and blood transfusion. Median quantitative blood loss differences were estimated by quantile regression and a Jonckheere-Terpstra trend test. Categorical outcomes were compared using Pearson χ2. Interactions with body mass index (BMI) and intrapartum oxytocin exposure were evaluated in multivariable regression. RESULTS: Of 1,094 vaginal births across three regimens (low: n=377; intermediate: n=349; high: n=368), the high-rate group had the lowest median [IQR] quantitative blood loss (365 mL [244-631 mL] vs 430 mL [260-735 mL] for the intermediate-rate group and 465 mL [285-725 mL] for the low-rate group; median difference of high vs low: -100 mL; 95% CI, -157 to -43; P=.001), with a monotonic trend across groups (P=.005). The high-rate group also required fewer second-line uterotonics (21.5% vs 29.4%, P=.047) than the low-rate group. Postpartum hemorrhage and transfusion rates did not differ. CONCLUSION: After vaginal birth, a high prophylactic oxytocin infusion rate was associated with less blood loss than intermediate or low rates.