A Trial of Trimethoprim–Sulfamethoxazole in Pregnancy to Improve Birth Outcomes

Maternal infections underlie several adverse birth outcomes. Whether trimethoprim-sulfamethoxazole prophylaxis during pregnancy will improve birth outcomes is unknown. In a double-blind, randomized, placebo-controlled trial in Zimbabwe, we assigned pregnant women to receive trimethoprim-sulfamethoxazole, at a dose of 960 mg daily, or placebo from at least 14 weeks' gestation until delivery. The primary outcome was birth weight. Among 993 participants (131 with human immunodeficiency virus infection), 498 were randomly assigned to receive placebo and 495 to receive trimethoprim-sulfamethoxazole, with the first dose received at a median of 21.7 weeks' gestation (interquartile range, 17.3 to 26.4). In intention-to-treat analyses, the mean (±SD) birth weight was 3040±460 g in the trimethoprim-sulfamethoxazole group and 3019±526 g in the placebo group (mean difference, 20 g, 95% confidence interval, -43 to 83; P = 0.53). The number of adverse events was similar in the two groups. In Zimbabwe, trimethoprim-sulfamethoxazole prophylaxis during pregnancy did not significantly increase infant birth weight. (Funded by Wellcome and others; Pan African Clinical Trials Registry number, PACTR202107707978619.).