The use of the Edmonton Obesity Staging System compared to body mass index to predict adverse pregnancy outcomes.

Background: In nonpregnant populations, obesity staging systems such as the Edmonton Obesity Staging System (EOSS) improve risk stratification of patients with obesity by also accounting for medical comorbidities. While the EOSS has been shown to better predict morbidity and mortality compared to body mass index (BMI)-based obesity classification in the nonpregnant population, its utility in pregnancy and performance compared to the current standard remain unclear. Thus, the objective of this study was to compare a modified EOSS and BMI-based obesity classification in predicting specific adverse pregnancy outcomes. Methods: We created a modified EOSS using available diagnoses within the Consortium on Safe Labor (CSL) dataset and applied it to all women with a prepregnancy BMI ≥ 30 kg/m Results: Among 228,668 subjects in the cohort, 139,126 pregnant individuals met inclusion criteria for analysis; 67,289 had BMI ≥ 30 kg/m Conclusions: A modified EOSS identified increased risk of adverse maternal and neonatal outcomes when applied to a pregnant population but did not demonstrate improved predictive ability compared to traditional BMI classification. Both EOSS and WHO BMI systems exhibited only poor-to-fair predictive ability for select adverse outcomes.