Oral Concurrent Session 5 - Clinical Obstetrics
Oral Concurrent Sessions
Taylor S. Freret, MD, MEd (she/her/hers)
Beth Israel Deaconess Medical Center
Brookline, Massachusetts, United States
.jpg "Ethan Litman, MD, MS (he/him/his) photo")
Ethan Litman, MD, MS (he/him/his)
Clinical Fellow
Beth Israel Deaconess Medical Center
Boston, Massachusetts, United States
Mark A. Clapp, MD, MPH (he/him/his)
Physician Investigator
Department of Obstetrics and Gynecology, Mass General Brigham
Boston, Massachusetts, United States
.jpeg.jpg "Sarah E. Little, MD, MPH photo")
Sarah E. Little, MD, MPH
Attending Physician
Beth Israel Deaconess Medical Center
Newton, Massachusetts, United States
The C/SOAP trial (late 2016) showed that perioperative azithromycin for cesarean birth after labor reduces postpartum infection. We sought to analyze the uptake and effect of azithromycin on postpartum infection in a nationwide cohort outside of a clinical trial.
Study Design:
This was a difference-in-differences (DID) analysis (2013-2024) using the nationwide Epic Cosmos platform. Laboring persons without IAI who gave birth to a liveborn singleton at 24-43 weeks were included. The primary exposure was perioperative azithromycin. In the DID design, cesarean births (treatment group) were compared to vaginal births (control group); the pre-period was 2013-2016, and the post-period 2017-2024. The primary outcome, adapted from the C/SOAP trial, was a composite of endometritis, wound infection, or other infection within 6 weeks, identified by ICD codes. The DID analysis used patient-level linear regression, adjusting for age, parity, delivery BMI, diabetes, prior cesarean birth, gestational age, ROM ≥ 18 hours, and reaching the second stage.
Results:
The cohort included 1,636,152 individuals; 212,030 (13.0%) delivered by cesarean. Azithromycin was administered to 73,969 (34.9%) of the cesarean and 442 (0.03%) of the vaginal births. There was a rapid increase in use among cesarean births after 2016, from 2.1% in 2013 to 61.2% in 2024 (Figure 1). There was no increase in use among vaginal deliveries. Among cesarean births, 6.8% who received azithromycin and 8.0% of those who did not developed an infectious complication (p< 0.001). The rate of infection increased from 1.9% to 2.6% among vaginal births and decreased from 8.6% to 7.4% among cesarean births between the two periods (Figure 2). In the adjusted DID analysis, azithromycin reduced the incidence of infectious complications by -2.1 [-2.3, -1.9] percentage points (~22% reduction).
Conclusion:
In a nationwide cohort, there was rapid uptake of azithromycin administration after cesarean birth, which decreased postpartum infectious complications. These findings demonstrate external validity of the C/SOAP trial findings in contemporary obstetric practice.