Body mass index and the risk of hypertensive disorders of pregnancy: the great obstetrical syndromes (GOS) study

Abstract

Objective To estimate the association between first-trimester body mass index (BMI) and the different types of hypertensive disorders of pregnancy (HDP). Methods A prospective cohort of nulliparous women recruited at 11–13 weeks. Height and weight were measured and BMI was reported as binary (more or less than 30 kg/m2), categorical (World Health Organization classification), and continuous variables. Participants were followed for development of any HDP, including preeclampsia and preterm preeclampsia. Receiver operating characteristic curves and their area under the curve (AUC) were used along with multivariate logistic regressions to develop predictive models combining BMI with other maternal characteristics. Results We recruited 4683 eligible participants including 645 (14%) affected by obesity. Obesity was associated with greater risks of HDP (22.5 versus 8.5%, p < .0001), preeclampsia (10.2 versus 4.3%, p < .0001), and preterm preeclampsia (1.6 versus 0.6%, p = .006). BMI categories (AUC: 0.65; 95%CI: 0.56–0.74) and BMI combined with maternal characteristics (AUC: 0.76; 95%CI: 0.69–0.83) were better predictors of preterm preeclampsia than BMI as binary variable (AUC: 0.58; 95%CI: 0.50–0.66). Conclusions Obesity and BMI are associated with the risk of all types of HDP. Optimal prediction of preterm preeclampsia is achieved by using BMI as a continuous variable combined with other maternal characteristics.