Severe maternal morbidity in the periviable period stratified by mode of delivery: a retrospective cohort study

Objective We sought to characterize the rate and type of severe maternal morbidity (SMM) among patients who delivered in the periviable period (20 0/7 through 25 6/7 weeks of gestation) and then to further stratify results by mode of delivery (cesarean versus vaginal). Design Single center retrospective cohort study of patients at the University of Cincinnati Medical Center delivering within the periviable between 2012 through 2021. Methods Maternal demographic and social factors, preexisting maternal co-morbidities, obstetric characteristics, interventions, and SMM were collected by three abstractors via manual chart review. SMM was defined according to ACOG’s example list. Differences in SMM between mode of delivery were compared using t-test and chi square analysis. Fisher’s exact test was used to compare counts equal to or less than 5. Main Outcome Measures Our primary outcome was the rate and type of severe maternal morbidity among patients who delivered in the periviable period. Our secondary outcome was this SMM stratified by mode of delivery. Results There were 338 periviable births among 289 patients during the study period. 152 (52.6%) underwent cesarean and 137 (47.4%) delivered vaginally. Overall rate of SMM among periviable births was 19.0%. The individuals delivered via cesarean section had higher rates of SMM (30.9% vs 5.8%, p<0.001, aOR 3.9, 95% CI 1.1-14.3). Conclusions One in five patients who delivered in the periviable period experienced a severe maternal morbidity, with almost a 4-fold higher risk among cesarean births compared to vaginal.