Carbetocin Uterotonic Treatment in Twin Pregnancies for Prevention of Postpartum Hemorrhage

Postpartum hemorrhage is a major cause of maternal morbidity worldwide and occurs more frequently in twin pregnancies compared with singleton deliveries. Uterine overdistension in multiple gestations increases the risk of uterine atony, the leading cause of postpartum hemorrhage. Preventive uterotonic therapy is therefore a central component of routine care following twin delivery.

Carbetocin is a long-acting synthetic analogue of oxytocin that induces sustained uterine contraction and is approved for the prevention of postpartum hemorrhage. Previous randomized trials and meta-analyses have demonstrated that carbetocin is associated with reduced need for additional uterotonic agents and blood transfusion compared with oxytocin, primarily in cesarean deliveries. However, data specific to twin pregnancies are limited, and no randomized controlled trial has directly compared carbetocin with standard oxytocin prophylaxis in a twin population including both vaginal and cesarean deliveries.

This single-center randomized controlled trial is designed to evaluate the effectiveness and safety of prophylactic carbetocin compared with standard oxytocin for the prevention of postpartum hemorrhage in twin deliveries. Pregnant individuals aged 18 years or older with twin pregnancies delivering at or beyond 23 weeks of gestation will be eligible to participate. Following written informed consent, participants will be randomized in a 1:1 ratio to receive either carbetocin or standard oxytocin immediately after delivery of the second twin.

Randomization will be performed using computer-generated permuted block sequences to ensure balanced group allocation. The assigned uterotonic treatment will be administered according to group assignment as part of routine postpartum care. Participants in the intervention group will receive a single intravenous dose of carbetocin, while participants in the control group will receive intravenous oxytocin according to institutional protocol.

Maternal hemoglobin levels will be obtained as part of routine clinical care prior to delivery and again on the first postpartum day. The primary outcome of the study is the change in maternal hemoglobin from before delivery to postpartum day one, serving as an objective measure of postpartum blood loss. Secondary outcomes include estimated blood loss, clinical postpartum hemorrhage, need for additional uterotonic agents, blood product transfusion, use of additional medical or surgical interventions for bleeding, maternal infections, intensive care unit admission, and length of postpartum hospitalization.

Participants will be followed throughout their delivery hospitalization and for up to six weeks postpartum to assess maternal outcomes and safety. Adverse events will be monitored by the clinical care team and reviewed in accordance with institutional policies. All data will be collected from the electronic medical record and stored in a secure, password-protected research database using unique study identifiers to maintain confidentiality.

The planned sample size is 120 participants, which is expected to provide sufficient power to detect a clinically meaningful difference in postpartum hemoglobin change between groups while ensuring adequate representation of both vaginal and cesarean deliveries. This trial aims to provide high-quality evidence regarding the role of carbetocin in preventing postpartum hemorrhage in twin pregnancies and to inform future clinical practice in this high-risk population.

Inclusion criteria

• Pregnant individuals aged ≥18 years
• Twin pregnancies
• Gestational age ≥23 weeks

Exclusion criteria

• Known hypersensitivity or contraindication to carbetocin
• Higher-order multiple gestation (triplets or more)
• Maternal age <18 years
• Known placenta accreta spectrum
• Known bleeding disorder
• Intrauterine fetal death of one or more fetuses
• Hyponatremia precluding oxytocin use
• Planned delivery at a non-participating hospital