The Effectiveness of Oxytocin for Preventing Postpartum Haemorrhage: An Individual Participant Data Meta-Analysis

Background: Post-partum haemorrhage (PPH) is a common complication of labour. Objective: To assess the effectiveness of oxytocin in comparison to no treatment for preventing PPH. Selection criteria: Published and unpublished randomised controlled trials (RCTs) comparing systemic oxytocin to placebo or no intervention for preventing PPH were included. We did not apply language restrictions. Search strategy: We identified RCTs from the Cochrane network meta-analysis on uterotonics for preventing PPH and updated the search via: Ovid MEDLINE, Embase via Ovid, Web of Science, CENTRAL, CINAHL Plus and clinicaltrials.gov. Data collection and analysis: An Individual participant data (IPD) meta-analysis. Main results: Of 14 eligible RCTs, four provided IPD (n = 4304; 51.7% received oxytocin and 48.4% received placebo or no intervention). Meta-analysis of IPD showed that oxytocin decreased the risk of PPH ≥ 500 mL (aOR 0.59; 95% CI 0.46 to 0.74) and PPH ≥ 1000 mL (aOR 0.51; 95% CI 0.32 to 0.80). Of 10 RCTs that did not share data, seven met trustworthiness criteria while three did not. Trustworthy IPD and aggregate data (AD) from RCTs meeting trustworthiness criteria (n = 6003) showed that oxytocin significantly reduced the rate of PPH ≥ 500 mL (aOR 0.53; 95% CI 0.45 to 0.62) and PPH ≥ 1000 mL (aOR 0.59; 95% CI 0.48 to 0.71). RCTs not meeting trustworthiness criteria reported a larger risk reduction of oxytocin for PPH ≥ 500 mL (n = 1027; aOR 0.37; 95% CI 0.03 to 4.03) and PPH ≥ 1000 mL (n = 1157; aOR 0.13; 95% CI 0.01 to 1.45). Conclusions: Prophylactic oxytocin reduces the risk of PPH ≥ 500 mL and PPH ≥ 1000 mL compared to no treatment. Twenty-one percent of RCTs did not meet our pre-defined trustworthiness criteria, underlining the importance of integrity assessment in evidence synthesis.