Intravenous carbetocin versus intravenous oxytocin for preventing atonic postpartum hemorrhage after normal vaginal delivery in high-risk singleton pregnancies: a triple-blind randomized controlled trial

Purpose: To compare the effectiveness of intravenous carbetocin to that of intravenous oxytocin for prevention of atonic postpartum hemorrhage (PPH) after vaginal delivery in high-risk singleton pregnancies. Methods: This triple-blind randomized controlled trial included singleton pregnant women who delivered at Siriraj Hospital between August 2016 and January 2017 and who were 20 years or older, had a gestational age of at least 34 weeks, had a vaginal delivery, and had at least one risk factor for atonic postpartum hemorrhage. Immediately after vaginal delivery, participants were randomly assigned to receive either 5 U of oxytocin or 100 mcg of carbetocin intravenously. Postpartum blood loss was measured objectively in mL using a postpartum drape with a calibrated bag. Results: A total of 174 and 176 participants constituted the oxytocin and carbetocin groups, respectively. The baseline characteristics were comparable between the groups. The carbetocin group had less postpartum blood loss (146.7 ± 90.4 vs. 195.1 ± 146.2 mL; p < 0.01), a lower incidence of atonic PPH (0 vs. 6.3%; p < 0.01), less usage of additional uterotonic drugs (9.1 vs. 27.6%; p < 0.01), and a lower incidence of postpartum anemia (Hb ≤ 10 g/dL) (9.1 vs. 18.4%; p < 0.05) than the oxytocin group. No significant differences regarding side effects were evident between the groups. Conclusions: Intravenous carbetocin is more effective than intravenous oxytocin for the prevention of atonic PPH among singleton pregnancies with at least one risk factor for PPH. Clinical trial registration: TCTR20160715004.