Polycystic ovary syndrome, body mass index and hypertensive disorders in pregnancy

Objective: Some studies of women with polycystic ovary syndrome (PCOS) report increased prevalence of hypertensive disorders in pregnancy, while others do not. Several of these studies do not control for obesity. We aimed to study whether PCOS is associated with hypertensive disorders in pregnancy and whether it is dependent on body mass index (BMI). Study design: We present a cross-sectional analysis of 3732 women from Denmark, Estonia, Iceland, Norway and Sweden, born in 1945-72, who participated in the Respiratory Health In Northern Europe (RHINE) study and answered an extensive women's health questionnaire on menstruation, PCOS, infertility, pregnancy history and childbirth. The main outcome measurement was hypertensive disorders of pregnancy. We adjusted for smoking, age, infertility treatment and study center. Effect modification by BMI was assessed. Results: PCOS was related to hypertensive disorders in pregnancy with a relative risk (RR) of 1.62 (95% CI 1.09-2.42). This relationship was found among underweight women with a BMI of <18.5 kg/m(2) [RR=5.2 (95% CI 1.66-16.5)] and obese women with a BMI of >= 30 kg/m(2) [RR=2.36 (95% CI 1.29-4.31)], but not among normal-weight women, BMI 18.5-25 kg/m(2) [1.08 (0.53-2.20)], or overweight women, BMI 25-30 kg/m(2) [1.24 (0.50-3.08)] (p-interaction=0.041). Conclusion: Polycystic ovary syndrome is associated with hypertensive disorders in pregnancy. This association only occurs among underweight and obese women and not among normal-weight and slightly overweight women.