The impact of change in pregnancy body mass index on the development of gestational hypertensive disorders

Abstract

To examine the impact of change in body mass index (BMI) during pregnancy on the incidence of gestational hypertension/preeclampsia. This is a retrospective cohort study using linked California birth certificate and discharge diagnosis data from the year 2007. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were calculated for the outcome of gestational hypertension/preeclampsia, as a function of a categorical change in pregnancy BMI: BMI loss (<-0.5), no change (-0.5 to 0.5), minimal (0.6 to 5), moderate (5.1 to 10) and excessive (>10). The impact of change in pregnancy BMI was evaluated for the entire cohort and then as a function of prepregnancy BMI category. Women with no change in pregnancy BMI served as the reference group. The study population consisted of 436 414 women with singleton gestations. Overall, women with excessive BMI change had a nearly twofold increased odds of gestational hypertension/preeclampsia (aOR=1.94; 95% CI=1.72 to 2.20). By prepregnancy BMI class, overweight and obese women who had a moderate change in pregnancy BMI also had increased odds of developing gestational hypertension/preeclampsia with aOR ranging from 1.73 to 1.97. Regardless of prepregnancy BMI category, women with excessive BMI change have a higher chance of developing gestational hypertension/preeclampsia. Overweight and obese women with moderate BMI change may also be at increased risk.