Study Finds Antibiotics During Pregnancy May Lower Preterm Birth Rates

Research involving nearly 1,000 expectant mothers in Zimbabwe suggests that a daily regimen of a widely used and affordable antibiotic could contribute to a decrease in preterm births. The study found that among women living with HIV, those who received the antibiotic exhibited a higher birth weight and a reduced likelihood of giving birth prematurely.

This research was published in the New England Journal of Medicine. It highlights a significant global health concern, as approximately one in four infants born alive globally is either preterm (defined as being born before 37 weeks of gestation), underweight for their gestational age, or has a low birth weight. Prematurity is now recognized as the leading cause of mortality among children under five years old, with many of these vulnerable infants facing a heightened risk of death.

Maternal infections and inflammation during pregnancy have been associated with negative birth outcomes, particularly for infants born to mothers who are HIV positive, who face increased risks of low birth weight and preterm delivery. An international team of researchers conducted the Cotrimoxazole for Mothers to Improve Birthweight in Infants (COMBI) randomized controlled trial to investigate whether prescribing pregnant women a daily dose of trimethoprim-sulfamethoxazole, an antimicrobial with anti-inflammatory properties commonly used in sub-Saharan Africa, would lead to heavier birth weights, fewer preterm births, and improved health outcomes for their infants.

Led by Professor Andrew Prendergast from Queen Mary University of London and Bernard Chasekwa from the Zvitambo Institute for Maternal and Child Health Research in Zimbabwe, the study recruited 993 pregnant women from three antenatal clinics in Shurugwi, a central district in Zimbabwe. Participants were assigned to receive either 960 mg of the antibiotic or a placebo on a daily basis while receiving regular antenatal care throughout their pregnancies.

While there was no significant difference in birth weight between the antibiotic and placebo groups, the group that received trimethoprim-sulfamethoxazole demonstrated a 40% reduction in the incidence of preterm births compared to those who received the placebo. Specifically, 6.9% of mothers in the antibiotic group had preterm births, compared to 11.5% in the placebo group, with no women in the antibiotic group delivering before 28 weeks of gestation.

Notably, among a subgroup of 131 women living with HIV, the antibiotic group saw an impressive reduction in preterm births, with only 2% experiencing premature delivery, in contrast to 14% in the placebo group. Additionally, infants exposed to the antibiotic during pregnancy showed an average increase in birth weight of 177 grams.

Chasekwa noted that while the primary outcome of increased birth weight was not achieved, there was a promising indication that the antibiotic may have prolonged gestation and decreased preterm deliveries. He emphasized the need for further trials in diverse settings worldwide to assess the potential of antibiotics during pregnancy in preventing preterm births.

Professor Prendergast, who specializes in Pediatric Infection and Immunology at Queen Mary, underscored the importance of these findings, suggesting that a low-cost daily antibiotic could significantly mitigate the risks of preterm births in regions where infections such as HIV are prevalent. With preterm birth rates being a leading cause of mortality in young children, confirming these results in subsequent studies could offer a new strategy for enhancing neonatal survival and health.

Sophie Hawksworth, Senior Manager of Clinical Discovery Research at Wellcome, highlighted the critical need to reduce preterm birth risks globally, especially in areas with limited access to neonatal intensive care facilities. Although the trial did not achieve its primary goal of increasing birth weight, the findings regarding the prevention of preterm births merit further investigation.

For more information, refer to the study published in the New England Journal of Medicine.