Tranexamic Acid to Prevent Obstetrical Hemorrhage after Cesarean Delivery.

BACKGROUND: Prophylactic use of tranexamic acid at the time of cesarean delivery has been shown to decrease the calculated blood loss, but the effect on the need for blood transfusions is unclear. METHODS: We randomly assigned patients undergoing cesarean delivery at 31 U.S. hospitals to receive either tranexamic acid or placebo after umbilical-cord clamping. The primary outcome was a composite of maternal death or blood transfusion by hospital discharge or 7 days post partum, whichever came first. Key secondary outcomes were estimated intraoperative blood loss of more than 1 liter (prespecified as a major secondary outcome), interventions for bleeding and related complications, the preoperative-to-postoperative change in the hemoglobin level, and postpartum infectious complications. Adverse events were assessed. RESULTS: A total of 11,000 participants underwent randomization (5529 to the tranexamic acid group and 5471 to the placebo group); scheduled cesarean delivery accounted for 50.1% and 49.2% of the deliveries in the respective groups. A primary-outcome event occurred in 201 of 5525 participants (3.6%) in the tranexamic acid group and in 233 of 5470 (4.3%) in the placebo group (adjusted relative risk, 0.89; 95.26% confidence interval [CI], 0.74 to 1.07; P = 0.19). Estimated intraoperative blood loss of more than 1 liter occurred in 7.3% of the participants in the tranexamic acid group and in 8.0% of those in the placebo group (relative risk, 0.91; 95% CI, 0.79 to 1.05). Interventions for bleeding complications occurred in 16.1% of the participants in the tranexamic acid group and in 18.0% of those in the placebo group (relative risk, 0.90; 95% CI, 0.82 to 0.97); the change in the hemoglobin level was -1.8 g per deciliter and -1.9 g per deciliter, respectively (mean difference, -0.1 g per deciliter; 95% CI, -0.2 to -0.1); and postpartum infectious complications occurred in 3.2% and 2.5% of the participants, respectively (relative risk, 1.28; 95% CI, 1.02 to 1.61). The frequencies of thromboembolic events and other adverse events were similar in the two groups. CONCLUSIONS: Prophylactic use of tranexamic acid during cesarean delivery did not lead to a significantly lower risk of a composite outcome of maternal death or blood transfusion than placebo. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development; ClinicalTrials.gov number, NCT03364491.).