Background: Postpartum haemorrhage (PPH) is the leading cause of maternal mortality. Uterotonics are the mainstay of PPH prevention. Objectives: To compare the efficacy of misoprostol and oxytocin for the prevention of PPH, and to evaluate the trustworthiness of trials comparing these uterotonics. Search strategy and selection criteria: Seven databases were searched for peer-reviewed literature, meeting the inclusion criteria of randomized controlled trials (RCTs) comparing misoprostol and oxytocin for the prevention of PPH. Data Collection and Analysis: Data were collected by two independent reviewers. Individual participant data (IPD) was meta-analyzed for outcomes PPH≥500mL and PPH≥1000mL. RCTs that did not share IPD were classified as trustworthy or not and were included in an aggregate data meta-analysis according to trustworthiness. Main results: Of 79 eligible RCTs, ten (12.7%) provided IPD, of which six were included. Analysis of IPD showed PPH≥500mL to be significantly higher in the misoprostol than the oxytocin group (2,022 women, aOR 1.84, 95% CI 1.43- 2.34). For PPH≥1000mL, analysis of IPD showed misoprostol and oxytocin were comparable (2022 women, OR 1.14, 95% CI 0.68- 1.91). Of the 69 studies that did not provide IPD, 23 (33.3%) were assessed as trustworthy. Analysis of trustworthy data (IPD and 23 aggregate data RCTs) showed no difference between misoprostol and oxytocin for PPH≥500mL (24,334 women, OR 1.01, 95% CI 0.69- 1.49), while misoprostol significantly increased the risk for PPH≥1000 (25,249 women, OR 1.36, 95% CI 1.16- 1.59). Conclusions: Of 79 RCTs comparing misoprostol and oxytocin for the prevention of PPH, 36.7% met trustworthiness criteria. Analysis of trustworthy data suggests oxytocin is superior to misoprostol for preventing PPH.