Higher-dose oxytocin to prevent obstetric hemorrhage at vaginal delivery-does duration of infusion matter?

Objective: Postpartum higher-dose oxytocin (80 U) compared with lower dose (10 U) given in 500 mL over 1 hour does not decrease postpartum hemorrhage (PPH) requiring treatment, but reduces the risk of hematocrit decline ≥ 6% among women delivering vaginally. Our objective was to evaluate whether the duration of administration of oxytocin influences outcomes.

Study Design: We compared a cohort receiving a postpartum oxytocin infusion of 80 U/500 mL over 1 hour to a concurrent cohort of women receiving 80 U/500 mL over 8 hours. The primary outcome was any treatment of PPH (uterotonics, blood transfusion, tamponade, and surgery). Secondary outcomes included pre- to postdelivery median hematocrit change and hematocrit decline ≥ 6%.

Results: There were 653 and 676 women identified in the 1- and 8-hour cohorts, respectively. There was no difference in PPH requiring any treatment between the 1- and 8-hour cohorts (6 vs. 6%, p = 0.70). There were no differences in individual treatment components including blood transfusion (p = 0.75). Median hematocrit decline (p = 0.02) was lower in the 8-hour cohort, but there was no difference in frequency of hematocrit decline ≥ 6% (p = 0.15). Results were unchanged by multivariable adjustments.

Conclusions: Postpartum higher-dose oxytocin administered over 1 hour compared with 8 hours was not associated with an increased treatment of PPH or frequency of hematocrit decline ≥ 6%.