Oral Concurrent Session 3 – Fetus and Fetal Intervention

Objective: In the Cesarean Section Optimal Prophylaxis (C/SOAP) trial, azithromycin (AZI) reduced puerperal infections by 50% compared to placebo (patients in both groups received standard cesarean antibiotic prophylaxis).However, concerns about AZI's effect on the neonatal microbiome and thus, long-term childhood health persist.As such, we compared childhood health outcomes in offspring from the C/SOAP trial after perinatal exposure to AZI versus placebo. Study Design:We performed a non-inferiority (NI) prospective follow-up study (from Jan 2021-July 2025) assessing health in children aged 7-14 of women enrolled in the original C/SOAP trial (2011-14).Children were compared by exposure to AZI or placebo.Our primary outcome was childhood obesity (BMI ≥95th percentile for age/sex).Secondary outcomes included select adverse respiratory and gastrointestinal (GI) outcomes.Risk differences (RD), with 95% confidence intervals [CI] were calculated and evaluated using a NI margin (NIM) of 10%.Multivariable analyses were planned a priori to adjust for known potential confounders.Results: Of the 2013 participants from C/SOAP, 1990 were eligible for follow-up, and 1024 were successfully contacted.Of those contacted, 505 children of these participants (49.3%) enrolled: 255 (50.5%) exposed to AZI and 250 (49.5%) placebo.Characteristics were similar between groups (Table 1).The rate of childhood obesity in the AZI group was non-inferior (adjusted RD -10.4%[-20% to -0.8%]; [-0.8%