A study proposes the use of antibiotics to prevent premature births.

A study of nearly 1,000 pregnant women in Zimbabwe found that taking a daily dose of a common, safe, and inexpensive antibiotic may have reduced the number of premature babies. Among women with HIV, the drug also resulted in babies being born larger and less likely to be premature.

One in four live births worldwide is premature (born at or before 37 weeks of gestation), small for their gestational age, or has a low birth weight. The mortality rate for these small and vulnerable newborns is high, and prematurity is currently the leading cause of death among children under 5 years of age. Maternal infections and inflammation during pregnancy are linked to adverse birth outcomes, particularly for babies born to mothers living with HIV, who are at increased risk of being born too small or too early.

In the study now published in The New England Journal of Medicine , an international group of researchers led by Andrew Prendergast of Queen Mary University of London , UK, and Bernard Chasekwa of the Zvitambo Institute for Maternal and Child Health Research in Zimbabwe , present the results of the Cotrimoxazole for Mothers to Improve Infants’ Birthweight (COMBI) randomized controlled trial. They examined whether prescribing pregnant women with once-daily treatment with trimethoprim-sulfamethoxazole (a broad-spectrum antimicrobial agent with anti-inflammatory properties that is widely used in sub-Saharan Africa) would result in higher birth weights, fewer preterm births, and better health outcomes for their babies.

A total of 993 pregnant women from three antenatal clinics in Shurugwi, a district in central Zimbabwe, participated and were given either 960 mg of the drug or a placebo daily. Participants received regular antenatal care throughout their pregnancy, and data on delivery outcomes were recorded.

Although there were no significant differences in birth weight between the groups overall, treatment with trimethoprim-sulfamethoxazole reduced the proportion of preterm births by 40% compared to placebo. Only 6.9% of treated mothers had premature babies compared to 11.5% in the placebo group, and none delivered before 28 weeks. In women with HIV, the reduction was even more pronounced : only 2% had premature births with treatment, compared to 14% with placebo. Furthermore, babies exposed to antibiotics during pregnancy weighed an average of 177 grams more at birth.

“Our trial showed that trimethoprim-sulfamethoxazole did not improve birth weight, which was our primary objective. However, there was an interesting hint that it may have improved pregnancy length and reduced the proportion of preterm births. We now need to repeat this trial in different settings around the world to see if antibiotics during pregnancy can help reduce the risk of prematurity ,” Chasekwa notes.

According to Prendergast, “The results suggest that a low-cost, daily antibiotic, in a setting where infections like HIV are common, could reduce the risk of premature birth. We desperately need new strategies to prevent premature birth, which is the leading cause of infant mortality in children under 5 years of age. If we can confirm in further trials that trimethoprim-sulfamethoxazole reduces the risk of babies being born too early, this would be a promising new approach to helping newborns survive and thrive.”