A study of almost 1 000 pregnant women in Zimbabwe found that a daily dose of a commonly used, safe and inexpensive antibiotic may have led to fewer babies being born early. Among women living with HIV, those who received the antibiotic had larger babies who were less likely to be preterm.
One in four live-born infants worldwide is preterm (born at 37 weeks; gestation or before); small for gestational age; or has a low birthweight. The mortality rate for these small and vulnerable newborns is high, with prematurity now the leading cause of death among children under five, reports News-Medical.net.
Maternal infections and inflammation during pregnancy are linked to adverse birth outcomes, particularly for babies born to mothers with HIV, who have a greater risk of being born too small or too soon.
An international group of researchers, led by Professor Andrew Prendergast from Queen Mary University of London, and statistician Bernard Chasekwa from the Zvitambo Institute for Maternal and Child Health Research in Zimbabwe, conducted the Cotrimoxazole for Mothers to Improve Birthweight in Infants (COMBI) randomised controlled trial. They examined whether prescribing pregnant women a daily dose of trimethoprim–sulfamethoxazole (a broad-spectrum antimicrobial agent with anti-inflammatory properties widely used in sub-Saharan Africa) would result in heavier birthweights, decreased premature births, and better health outcomes for their babies.
A total of 993 pregnant women were recruited from three antenatal clinics in Shurugwi, central Zimbabwe, and received either 960mg of the drug or a placebo daily. The participants received regular antenatal care during their pregnancies and data regarding their birth outcomes were recorded.
Although birthweight did not differ significantly between the two groups, the trimethoprim–sulfamethoxazole group showed a 40% reduction in the proportion of preterm births, compared with the placebo group.
Overall, 6.9% of mothers receiving the drug had babies born preterm, compared with 11.5% of mothers receiving the placebo, and no women receiving antibiotics had babies born before 28 weeks.
For babies born to a small group of 131 women with HIV, the reduction in premature births was especially marked, with only 2% of births in the trimethoprim–sulfamethoxazole group preterm, compared with 14% in the placebo group.
Babies exposed to antibiotics during pregnancy also showed a 177g increase in their birthweight.
“Our trial, conducted within routine antenatal care and enrolling women predominantly from rural areas, showed that trimethoprim-sulfamethoxazole did not improve birthweight, which was our main outcome.
“However, there was an intriguing suggestion that it may have improved the length of pregnancy and reduced the proportion of preterm births. We now need to repeat this trial in different settings around the world to see whether antibiotics during pregnancy can help reduce the risk of prematurity,” noted Chasekwa, first author.
Prendergast, Professor of Paediatric Infection and Immunology at Queen Mary, said: “Our findings suggest that a low-cost, daily antibiotic, in a setting where infections like HIV are common, might reduce the risk of preterm births. We desperately need new strategies to prevent preterm births, which are the leading cause of under-five child mortality.
“If we can confirm in other trials that trimethoprim-sulfamethoxazole reduces the risk of babies being born too soon, it would be a promising new approach to help newborns survive and thrive.”
Sophie Hawksworth, senior manager of clinical discovery research at Wellcome, said: “If we are to reduce child mortality globally, it is critical to reduce the risk of preterm births, especially in areas with limited access to neonatal intensive care units and resources.
“This is a promising study and while the primary outcome of birthweight was unaffected in the trial, the prospect that this treatment prevents preterm births warrants further study.”
Study details
Trial of Trimethoprim–Sulfamethoxazole in Pregnancy to Improve Birth Outcomes
Bernard Chasekwa, Fortunate Munhanzi, Lenin Madhuyu et al.
Published in New England Journal of Medicine on 4 June 2025
Abstract
Background
Maternal infections underlie several adverse birth outcomes. Whether trimethoprim–sulfamethoxazole prophylaxis during pregnancy will improve birth outcomes is unknown.
Methods
In a double-blind, randomised, 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 birthweight.
Results
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.
Conclusions
In Zimbabwe, trimethoprim–sulfamethoxazole prophylaxis during pregnancy did not significantly increase infant birthweight.
News-Medical.net article – Common antibiotic shows promise in reducing preterm births (Open access)
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