Maternal super obesity and risk for intensive care unit admission in the MFMU Cesarean Registry

Introduction: Obesity is a risk factor for intensive care unit (ICU) admission in nonpregnant populations. Less is known about maternal obesity and ICU admission risk. The objective of this study was to estimate the association between maternal obesity and ICU admission among women who delivered via cesarean section or vaginal birth after cesarean section (VBAC). Material and methods: This is a retrospective cohort analysis of women who delivered via VBAC or cesarean section in the Maternal–Fetal Medicine Unit (MFMU) Cesarean Registry. We defined exposure as body mass index (BMI) at delivery stratified as non-obese (BMI 18.5–29.9 kg/m²), class I or II obese (BMI 30–39.9 kg/m²), morbidly obese (BMI 40–49.9 kg/m²), and super obese (BMI ≥ 50 kg/m²). The primary outcome was ICU admission. Modified Poisson regression models estimated relative risk (RR) of ICU admission by obesity strata, after adjusting for confounders. Mediation analysis was used to estimate the proportion of ICU admission risk attributable specifically to obesity. Results: We included 68 455 women; 40% non-obese, 46% class I or II obese, 12% morbidly obese, and 2% super obese. Super obese women were at higher risk for ICU admission compared with non-obese women (0.7 vs. 1.3%, adjusted RR 1.61; 95% CI 1.01–2.65), after adjusting for confounders. Among super obese women, medical comorbidities mediated 58% of ICU admission risk, suggesting that a significant proportion of ICU admission is driven by maternal obesity. Conclusions: Super obese women who deliver by cesarean section or VBAC are at increased risk of peripartum ICU admission. Obstetricians and critical care specialists should consider possible ICU admission during delivery planning.