Inclusion Criteria:  BMI≥40 kg/m2 Elective cesarean delivery under spinal, epidural, or combined spinal-epidural anaesthesia Written informed consent Full term pregnancy (37+0 to 40+6 weeks gestation) Non-labouring patients  Exclusion Criteria:  Refusal to give written informed consent Allergy or hypersensitivity to carbetocin or oxytocin Laboring patients Need for general anaesthesia Conditions that predispose to uterine atony and postpartum haemorrhage including but not limited to: Placenta previa Multiple gestations Preeclampsia Eclampsia Polyhydramnios Uterine fibroids Previous history of uterine atony and postpartum bleeding Bleeding diathesis Hepatic, renal, and cardiovascular disease