Infection can develop in up to 10-20% of patients after a Cesarean delivery, and the risk nearly doubles for those who have an unplanned cesarean delivery, such as those performed during labor. In 2016, researchers published the results of a double-blind, randomized clinical trial of patients undergoing an emergency c-section in which half of participants received intravenous azithromycin in addition to routine antibiotics. Compared to those in the placebo group, those in the azithromycin group had a 50% lower rate of infections (12% versus 6%). But the extent to which the trial's results have since changed clinical practice has been unknown.
To address this, researchers from Mass General Brigham, led by former maternal-fetal medicine fellow Taylor S. Freret, MD, MEd, under the supervision of Mark A. Clapp, MD, MPH, examined uptake of azithromycin for emergency c-sections after 2016 and whether there was an associated decrease in postpartum infection rates. The team used data from Epic Cosmos to compare rates between 2013 and 2016 to rates between 2017 and 2024.
The researchers found that azithromycin use significantly increased — it was administered in 2.2% of emergency c-sections pre-2016 and in 39.6% of cases in the later period. Postpartum infection rates also declined from 9.2% to 8.0%, a relative risk reduction of 20%.
While the researchers observed a smaller relative decrease in risk of infection compared to the trial, this is in part due to the fact that only about half of patients who had an unplanned c-section received azithromycin. Overall, azithromycin use has increased, and infection rates have decreased after the trial's publication, supporting the effectiveness and generalizability of this practice in real-world clinical settings.
