Background: Oral misoprostol, administered by trained health-workers is effective and safe for preventing postpartum haemorrhage (PPH). There is interest in expanding administration of misoprostol by non-health workers, including task-shifting to pregnant women themselves. However, the use of misoprostol for preventing PPH in home-births remains controversial, due to the limited evidence to support self-administration or leaving it in the hands of non-health workers. This study aimed to determine if antenatally distributing misoprostol to pregnant women to self-administer at home birth reduces PPH. Methods: Between February 2013 and March 2014, we conducted a stepped-wedge cluster-randomized trial in six health facilities in Central Uganda. Women at 28+ weeks of gestation attending antenatal care were eligible. Women in the control-arm received the standard-of-care; while the intervention-arm were offered 600mcg of misoprostol to swallow immediately after birth of baby, when oxytocin was not available. The primary outcome (PPH) was a drop in postpartum maternal haemoglobin (Hb) by >= 2g/dl, lower than the prenatal Hb. Analysis was by intention-to-treat at the cluster level and we used a paired t-tests to assess whether the mean difference between the control and intervention groups was statistically significant. Results: 97% (2466/2545) of eligible women consented to participate; 1430 and 1036 in the control and intervention arms respectively. Two thousand fifty-seven of the participants were successfully followed up and 271 (13.2 %) delivered outside a health facility. There was no significant difference between the study group in number of women who received a uterotonic at birth (control 80.4 % vs intervention 91.4 %, mean difference = -11.0 %, 95 % confidence interval [CI] -25.7 % to 3.6 %, p = 0.11). No woman took misoprostol before their baby's birth. Shivering and fever were 14.9 % in the control arm compared to 22.2 % in the intervention arm (mean difference = -7.2 %, 95 % CI -11.1 % to -3.7 %), p = 0.005). There was a slight, but non-significant, reduction in the percentage of women with Hb drop >= 2g/dl from 18.5% in the control arm to 11.4 % in the intervention arm (mean difference = 7.1 %, 95% CI -3.1 % to 17.3 %, p = 0.14). Similarly, there was no significant difference between the groups in the primary outcome in the women who delivered at home (control 9.6 % vs intervention 14.5 %, mean difference -4.9; 95 % CI -12.7 to 2.9), p = 0.17). Conclusion: This study was unable to detect a significant reduction in PPH following the antenatal distribution of misoprostol.