Neonatal mortality rates were 0.4% (n=67) for vaginal births and 0.1% (n=102) for cesarean births (RD 0.3; 95% CI, 0.2-0.4). Risk of the composite adverse maternal outcome (excluding perineal lacerations) was 0.3% for vaginal births and 0.5% for cesarean breech births (RD -0.4, 95% CI, -0.5 to -0.3)

The primary contributor to neonatal morbidity within the vaginal breech cohort was 5-minute Apgar score less than 4 (RD 1.6; 95% CI, 1.4-1.9). Other neonatal outcomes were not different.

The risks of the composite adverse neonatal outcome were 7.2% in the vaginal delivery group, compared with 6.3% in the cesarean delivery group (risk difference [RD] 1.0; 95% CI, 0.9-1.2; doubly robust odds ratio 1.14; 95% CI, 1.06-1.22).

Of 23,118,953 singleton births, 375,500 term, nonanomalous, breech live births were identified. 5.1% (95% CI, 5.0-5.2; n=19,256) were vaginal deliveries. After propensity score matching, the final cohort comprised 96,095 patients, including 17,558 vaginal deliveries and 78,537 cesarean deliveries.

Short-term maternal outcomes were better for individuals who underwent vaginal delivery compared with cesarean delivery, after exclusion of perineal lacerations.