Intramuscular versus intravenous oxytocin to prevent postpartum haemorrhage at vaginal delivery: randomised controlled trial

Abstract

OBJECTIVE: To determine whether intravenous oxytocin is more effective than intramuscular oxytocin at preventing postpartum haemorrhage at vaginal delivery. DESIGN: Double blind placebo controlled randomised trial. SETTING: University affiliated maternity unit in the Republic of Ireland. PARTICIPANTS: 1075 women aged 18 years or older, at term with a singleton pregnancy who were aiming for a vaginal delivery with an actively managed third stage of labour. INTERVENTIONS: Women were allocated to an intravenous bolus of oxytocin (10 IU in 1 mL given slowly over one minute) and placebo intramuscular injection (1 mL 0.9% saline) or an intramuscular bolus of oxytocin (10 IU in 1 mL) and placebo intravenous injection (1 mL 0.9% saline given slowly over one minute) at vaginal delivery. Allocation was by a secure web based randomisation service with masking of participants and clinicians to the trial intervention. MAIN OUTCOME MEASURES: The primary outcome was postpartum haemorrhage (PPH, measured blood loss ≥500 mL). Secondary outcomes were severe PPH (measured blood loss ≥1000 mL), need for blood transfusion, admission to a high dependency unit, and side effects to oxytocin. RESULTS: 5.2%, 0.75, 0.42 to 1.35). CONCLUSION: Intravenous oxytocin for the third stage of labour results in less frequent severe PPH, blood transfusion, and admission to a high dependency unit than intramuscular oxytocin, and without excess side effects. TRIAL REGISTRATION: Current Controlled Trials ISRCTN14718882.