"Increasing Body Mass Index is Associated with Intensive Care Unit Admission and Severe Maternal Morbidity"

Objective: This study aimed to assess the relationship between increased body mass index (BMI) with severe maternal morbidity (SMM).

Study Design: We obtained data for a retrospective cohort of singleton live births using an electronic birth certificate database from 2010 to 2022 in Central New York. Institutional review board exemption was obtained. Pre-pregnancy BMI was assessed as a continuous variable and a categorical variable with groups of BMI <18.5 kg/m, 30-39.9 kg/m, 40-49.9 kg/m, and ≥50 kg/m compared to patients with BMI 18.5-29.9 kg/m. Primary outcomes were maternal intensive care unit (ICU) admission and composite SMM defined as ICU admission, unplanned hysterectomy, reoperation, eclampsia, and blood transfusion. Secondary outcomes were the individual SMM components, 5-minute APGAR score <7, and neonatal intensive care unit (NICU) admission. ANOVA and χ were used to compare continuous and categorical variables respectively, and logistic regression was used to obtain adjusted odds ratios for primary and secondary outcomes.

Results: There were 223,837 patients with singleton live births with mean BMI 27.86 kg/m. 54,385 (24.3%) had BMI 30-39.9 kg/m, 13,299 (5.9%) had BMI 40-49.9 kg/m, and 1,958 (0.87%) had BMI ≥50 kg/m. 3,203 (1.4%) patients experienced SMM, and 423 (0.2%) patients were admitted to ICU. For each 1-point increase in BMI the adjusted odds ratio (aOR) of SMM increased by 0.8% (aOR 1.008, 95% CI 1.002-1.013) and ICU admission increased by 2.0% (aOR 1.02, 95% CI 1.005-1.034). Odds of ICU admission for those with BMI 40-49.9 kg/m increased by 69% (aOR 1.69, 95% CI 1.16-2.47); BMI ≥50 kg/m increased by 300% (aOR 3.01, 95% CI 1.53-5.91), but those with BMI 30-39.9 kg/m did not have significantly higher odds of ICU admission (aOR 1.09, 95% CI 0.84-1.42).

Conclusion: Increasing BMI was significantly associated with increased SMM and maternal ICU admission.