To compare the available evidence on intravenous oxytocin dosing regimens for the prevention of postpartum hemorrhage following cesarean delivery.

We searched Ovid MEDLINE, Embase, Global Index Medicus, Cumulative Index of Nursing and Allied Health Literature, Cochrane Controlled Register of Trials, ClinicalTrials.gov, and the International Clinical Trials Registry Platform for eligible studies published until February 2020.

We included any randomized or nonrandomized study published in peer-reviewed journals that compared at least 2 different dosing regimens of intravenous oxytocin for postpartum hemorrhage prevention in women undergoing cesarean delivery.

Two authors independently assessed the eligibility of studies, extracted the data, and assessed the risk of bias. The primary outcome was incidence of postpartum hemorrhage ≥1000 mL. Other review outcomes included use of additional uterotonics, blood loss, and adverse maternal events. Data were analyzed according to the type of intravenous administration (bolus only, infusion only, or bolus plus infusion) and total oxytocin dose. A meta-analysis was performed on randomized trials and the results were reported as risk ratios or mean differences with 95% confidence intervals. The Grading of Recommendations, Assessment, Development, and Evaluations scale was used to rate the certainty of evidence. Findings from dose-finding trials and nonrandomized studies were reported narratively.

A total of 35 studies (7333 women) met our inclusion criteria and included 30 randomized trials and 5 nonrandomized studies. There were limited data available from the trials for most outcomes, and the results were not conclusive. Compared with bolus plus infusion regimens, bolus only regimens probably result in slightly higher mean blood loss (mean difference, 52 mL; 95% confidence interval, 0.4–104 mL; moderate certainty). Among the bolus plus infusion regimens, initial bolus doses <5 IU may reduce nausea (risk ratio, 0.26; 95% confidence interval, 0.11–0.63; low certainty) when compared with doses of 5–9 IU. Total oxytocin doses of 5–9 IU vs total doses of 10–19 IU may increase the use of additional uterotonics (risk ratio, 13.00; 95% confidence interval, 1.75–96.37; low certainty). Effects on other outcomes were generally inconclusive.

There are limited data available for comparisons of IV oxytocin regimens for postpartum hemorrhage prevention following cesarean delivery. Bolus plus infusion regimens may lead to minor reductions in mean blood loss and initial bolus doses of <5 IU may minimize nausea. Bolus only regimens of 10 IU vs bolus only regimens of 5 IU may decrease the need for additional uterotonics, however, further comparative trials are required to understand the effects on other key outcomes, particularly hypotension.