Dose–response evaluation of intravenous carbetocin for prevention of postpartum haemorrhage during elective caesarean delivery: A parallel-group randomised controlled trial

Background and Aims: Postpartum haemorrhage (PPH) is a major cause of maternal morbidity and mortality. Although 100 μg intravenous carbetocin is commonly administered for uterotonic prophylaxis at caesarean delivery, the optimal dose remains uncertain. The primary objective was to evaluate the dose–response relationship of intravenous carbetocin in achieving adequate uterine tone during elective caesarean delivery. Methods: In this randomised, parallel-group, dose–response trial, 100 parturients scheduled for elective caesarean delivery were assigned into five groups to receive intravenous carbetocin at doses of 100 μg, 80 μg, 60 μg, 40 μg, or 20 μg ( n = 20 per group) immediately after foetal delivery. The primary outcome was satisfactory uterine tone at 2, 5, and 10 minutes. Secondary outcomes included blood loss, requirement for additional uterotonics, PPH incidence, blood transfusion, haemodynamic variables, and adverse events. Trend analysis assessed dose–response relationships. Results: Baseline demographic and obstetric characteristics were comparable among groups. Uterine contraction increased progressively from 75% to 85% at 2 minutes to 90–95% at 5 minutes and 95–100% at 10 minutes, with no significant intergroup differences ( P = 0.960, 0.921, and 0.724, respectively). Mean blood loss and requirement for additional uterotonics were similar across groups. The incidence of PPH, need for blood transfusion, haemodynamic variables, and adverse events were comparable. No significant dose–response relationship was observed. Conclusion: In low-risk, non-obese women undergoing elective caesarean delivery under spinal anaesthesia, intravenous carbetocin doses ranging from 20 μg to 100 μg resulted in similar uterotonic response and blood-loss outcomes, with no statistically significant differences between the different dose groups.