Effects of tranexamic acid preconditioning on the incidence of postpartum haemorrhage in vaginal deliveries with identified risk factors in China: a prospective, randomized, open-label, blinded endpoint trial

Objective: This study aimed to evaluate the effects of tranexamic acid (TXA) in preventing postpartum haemorrhage (PPH) among women with identified risk factors for PPH undergoing vaginal delivery in China. Methods: This prospective, randomized, open-label, blinded endpoint (PROBE) trial enrolled 2258 women with one or more risk factors for PPH who underwent vaginal delivery. Participants were randomly assigned in a 1:1 ratio to receive an intravascular infusion of 1 g TXA or a placebo immediately after the delivery of the infant. The primary outcome assessed was the incidence of PPH, defined as blood loss >= 500 mL within 24 h after delivery, while severe PPH was considered as a secondary outcome and defined by total blood loss >= 1000 mL within 24 h. Results: 2245 individuals (99.4%) could be followed up to their primary outcome. PPH occurred in 186 of 1128 women in the TXA group and in 215 of 1117 women in the placebo group (16.5% vs. 19.2%; RR, 0.86; 95% CI, 0.72 to 1.02; p = 0.088). Regarding secondary outcomes related to efficacy, women in the TXA group had a significant lower rate of severe PPH than those in the placebo group (2.7% vs. 5.6%; RR, 0.49; 95% CI, 0.32 to 0.74; p = 0.001; adjusted p = 0.002). Similarly, there was a significant reduction in the use of additional uterotonic agents (7.8% vs. 15.6%; RR, 0.50; 95% CI, 0.39 to 0.63; p < 0.001; adjusted p = 0.001). No occurrence of thromboembolic events and maternal deaths were reported in both groups within 30 days after delivery. Conclusions: In total population with risk factors for PPH, the administration of TXA following vaginal delivery did not result in a statistically significant reduction in the incidence of PPH compared to placebo; however, it was associated with a significantly lower incidence of severe PPH.