Prepregnancy body mass index, hypertensive disorders of pregnancy, and long-term maternal mortality.

OBJECTIVE: Recent studies have shown increased maternal mortality rates after hypertensive disorders of pregnancy (HDP), but the reasons for this increase remain unclear. This study examines the relationship between elevated prepregnancy body mass index (BMI), HDP, and postpregnancy mortality.

STUDY DESIGN: Data came from a 1975-1976 subset (n = 13,722 women) of a population-based cohort. Multiple logistic regression was used to examine the risk of HDP by BMI; age-adjusted Cox proportional hazards models were used to examine survival rates.

RESULTS: Overweight (BMI, 25-29.9 kg/m2) and obesity (BMI, > or = 30 kg/m2) were associated with increased HDP (odds ratio [OR], 2.82; 95% confidence interval [CI], 2.40-3.31 and OR, 5.51; 95% CI, 4.15-7.31]) and decreased survival (hazard ratio [HR], 1.42; 95% CI, 1.10-1.83 and HR, 2.43; 95% CI, 1.61-3.68), compared with normal weight (BMI, 18.5-24.9 kg/m2). HDP was significantly associated with increased mortality rates for women who survived > 15 years (HR, 1.94; 95% CI, 1.42-2.67]; HR adjusted for BMI, 1.65; 95% CI, 1.19-2.79]). A greater increase in risk of death after HDP was seen in the overweight women (HR, 1.86; 95% CI, 1.07-3.20) and obese women (HR, 2.90; 95% CI, 1.28-6.58), compared with normal weight women (HR, 1.26; 95% CI, 0.74-2.14).

CONCLUSION: Elevated prepregnancy BMI is associated with increased risk of HDP, which are in turn is associated with increased long-term maternal mortality rates. This association between HDP and mortality rates increases with elevated prepregnancy BMI.