STUDY DESIGN: Participants were randomized to intravenous bolus injection of 100mcg carbetocin or 10IU oxytocin after cesarean delivery of the baby. The primary outcome is any additional uterotonic which may be administered by the blinded provider for perceived inadequate uterine tone with or without hemorrhage in the first 24hours after delivery. Secondary outcomes include operating time, perioperative blood loss, change in hemoglobin and hematocrit levels, blood transfusion and reoperation for postpartum hemorrhage.

RESULTS: Additional uterotonic rates were 107/276 (38.8%) vs. 155/271 (57.2%) [RR 0.68 95% CI 0.57-0.81 p<0.001; NNTb 6 95% CI 3.8-9.8], mean operating time 45.9±16.0 vs. 44.5±13.1minutes p=0.26, mean blood loss 458±258 vs. 446±281ml p=0.6, severe postpartum hemorrhage (≥1000ml) rates 15/276 (5.4%) vs. 10/271 (3.7%) p=0.33 and blood transfusion rates 6/276 (2.2%) vs. 10/271 (3.7%); p=0.30 for carbetocin and oxytocin arms respectively. There was only one case of re-operation (oxytocin arm). In the cases that needed additional uterotonic 98% (257/262) was started intraoperatively and in 89% (234/262) the only additional uterotonic administered was an oxytocin infusion over 6hours.