(955) Association Between Body Mass Index and Maternal Outcomes Following Uterine Rupture

This retrospective cohort study used a national U.S. obstetric database to identify 4,034,543 deliveries, of which 5,253 were complicated by uterine rupture. Patients were stratified by BMI category: underweight, normal weight, overweight, class I, class II, and class III obesity. The primary outcomes were maternal ICU admission, transfusion, and hysterectomy. Multivariable logistic regression was performed to estimate adjusted odds ratios (aOR) for each outcome by BMI category, using normal BMI as the reference and adjusting for confounders including hypertensive disorders, diabetes, maternal age, and number of prior cesareans.

Results:

Uterine rupture occurred most frequently among underweight individuals (0.19%) compared to other BMI categories (range: 0.11–0.15%). Among patients with uterine rupture, underweight individuals had significantly increased odds of maternal ICU admission (aOR 1.24, 95% CI 1.07–1.44), blood transfusion (aOR 1.24, 95% CI 1.14–1.36), and hysterectomy (aOR 1.31, 95% CI 1.07–1.60). Class III obesity was also associated with increased ICU admission (aOR 1.20, 95% CI 1.12–1.29), but not with increased odds of transfusion or hysterectomy. Overweight and class I obesity were associated with significantly decreased odds of transfusion compared to normal BMI.

Conclusion:

Underweight BMI is associated with the highest rate of uterine rupture and greater maternal morbidity, including higher rates of ICU admission, transfusion, and hysterectomy. Class III obesity is similarly associated with increased risk for ICU-level care. These findings highlight the need for vigilant peripartum management of patients at both ends of the BMI spectrum.