Researchers looked at data from a large international trial involving over 29,000 pregnant people in labor who were planning vaginal delivery. They wanted to know if the timing of giving a single dose of the antibiotic azithromycin affected how well it worked to prevent infections in mothers and their newborns.
The study found that giving azithromycin during labor reduced the risk of maternal infections by about 29% overall, and this benefit did not depend on how long before delivery the antibiotic was given. However, in a smaller subgroup of participants from Sub-Saharan Africa, the benefit appeared stronger when the antibiotic was given more than 12 hours before delivery. Importantly, the antibiotic showed no benefit in preventing infections in newborns, regardless of timing.
This was a secondary analysis, meaning researchers were looking at existing trial data in a new way rather than conducting a new study specifically designed to answer this timing question. The finding about stronger benefit with longer timing in Sub-Saharan Africa comes from a subgroup analysis, which is less reliable than the main trial results. Readers should understand that while this analysis provides helpful information, it doesn't change the main finding from the original trial: azithromycin helps prevent maternal infections but not newborn infections.