Replacement of oxytocin bolus administration by infusion: influences on adverse postpartum outcome

Objective: Postpartum haemorrhage (PPH) represents a leading cause of maternal morbidity and mortality. Giving oxytocin after birth reduces the risk for PPH. It has never been tested, whether different methods of oxytocin administration affect maternal outcome.

This study aims to compare the incidence of postpartum complications in women receiving an infusion or a bolus of oxytocin after vaginal delivery.

Methods: Retrospective study including 1765 women delivering singletons vaginally at term. Patients were classified into two groups; those who received 5 IU of oxytocin as an intravenous bolus or as a 100 ml-infusion over 5 min immediately after birth.

Primary outcome: incidence of one of the following events: PPH, manual removal of the placenta (MRP) and/or curettage.

Secondary outcomes: incidence of PPH, MRP, curettage, severe PPH, placenta retention, uterine atony, erythrocyte transfusion, transfer to the intensive care unit, duration of the third stage of labour, estimated blood loss (EBL), decrease of serum haemoglobin.

Data analysis: comparison of the outcomes and propensity score weighted analysis.

Results: Patient characteristics were quite balanced. We found no significant differences in primary outcome. Within the secondary outcomes we observed a higher frequency of MRP (odds ratio 1.47, 95% CI 1.02 – 2.13) and a larger EBL (relative effect 1.05, 95% CI 1.01 – 1.10) in the infusion group.

Conclusion: There was a tendency towards more adverse outcomes in the infusion group. This does not concern the primary outcome, but is related to a more frequent need for MRP and a higher peripartal blood loss.