Associations between body mass index and development of metabolic disorders in fertile women--a nationwide cohort study.

Background: Metabolic disorders are relatively uncommon in young women, but may increase with obesity. The associations between body mass index (BMI) and risks of diabetes, hypertension, and dyslipidemia in apparently healthy, young women have been insufficiently investigated, and are the aims of this study.

Methods And Results: Women giving birth during the years 2004-2009, with no history of cardiovascular disease, renal insufficiency, pregnancy-associated metabolic disorders, diabetes, hypertension, or dyslipidemia were identified in nationwide registers. Women were categorized as underweight (BMI<18.5 kg/m(2)), normal weight (BMI=18.5 to <25 kg/m(2)), overweight (BMI=25 to <30 kg/m(2)), obese-I (BMI=30 to <35 kg/m(2)), obese-II (BMI=35 to <40 kg/m(2)), and obese-III (BMI≥40 kg/m(2)). We assessed risks by Poisson regression models (adjusted for age, calendar year; reference=normal weight). The cohort comprised 252 472 women with a median age of 30.4 years (IQR=27.2;33.7) and a median follow-up of 5.5 years (IQR=3.9;6.8). In total, 2029 women developed diabetes, 3133 women developed hypertension, and 1549 women developed dyslipidemia. Rate ratios (RRs) of diabetes were: 0.84 (95% confidence interval [CI]=0.62 to 1.14) for underweight, 2.63 (CI=2.36 to 2.93) for overweight, 4.83 (CI=4.27 to 5.47) for obese grade-I, 7.17 (CI=6.10 to 8.48) for obese grade-II, and 6.93 (CI=5.47 to 8.79) for obese grade-III women. For hypertension, corresponding RRs were 0.86 (CI=0.69 to 1.09), 1.82 (CI=1.67 to 1.98), 2.81 (CI=2.52 to 3.13), 3.92 (CI=3.36 to 4.56), and 5.69 (CI=4.71 to 6.89), and for dyslipidemia, RRs were 1.18 (CI=0.85 to 1.65), 2.01 (CI=1.75 to 2.31), 3.11 (CI=2.61 to 3.70), 4.64 (CI=3.66 to 5.87), and 3.72 (CI=2.53 to 5.48).

Conclusions: In this nationwide study of fertile, apparently healthy women, pre-pregnancy BMI was strongly associated with an increased risk of diabetes, hypertension, and dyslipidemia within 5.5 years following childbirth.