Exploring the Effects of Obesity on Postpartum Hemorrhage Risk

This study aims to analyze rates of postpartum hemorrhage according to body mass index (BMI) and investigate relative risks for postpartum hemorrhage based on BMI.

We conducted a retrospective chart review of all deliveries occurring in 2022 at two large urban hospitals in Indianapolis, IN, resulting in a cohort of 5,686 patients. After excluding patients for missing data, a total of 4,493 patients were included in the final analysis. Patients were categorized according to the Centers for Disease Control and Prevention (CDC) BMI definitions. We analyzed rates of postpartum hemorrhage according to patient variables.

The rates of postpartum hemorrhage for patients with BMI categorized as healthy weight, overweight, Class I obesity, Class II obesity, and Class III obesity were 16.3, 19.6, 23.0, 21.3, and 27.7%, respectively (p < 0.0001). Relative risk for postpartum hemorrhage by BMI categories was investigated using logistic regression analysis, where patients in the healthy weight cohort (BMI 18 to <25) were used as the reference for risk of postpartum hemorrhage. We found that patients with Class III obesity had an increased risk of postpartum hemorrhage by 57% after adjusting for mode of delivery and race (adjusted risk ratio [aRR] = 1.57, 95% CI: 1.20-2.04). Despite increased relative risk in all categories, we found no statistical significance for patients with BMI in the overweight category (aRR = 1.19, 95% CI: 0.92-1.54) or the Class II obesity category (aRR = 1.24, 95% CI: 0.05-1.63).

This study shows a significantly increased risk of postpartum hemorrhage among obese patients, particularly those with Class III obesity. Notably, we did not observe a dose-dependent effect of BMI on rates of postpartum hemorrhage, as there was, in fact, a marginal decrease in rates of postpartum hemorrhage when comparing Class I and Class II obesity. This study supports risk-based initiatives to address increasing postpartum hemorrhage rates in the United States.

· The relationship between obesity and postpartum hemorrhage was investigated.. · There was an increase in postpartum hemorrhage after 40+ BMI.. · Mode of delivery and maternal age also alter postpartum hemorrhage risk.. · These data support the use of risk-assessment tools for obesity..