The relationship between weight gain during pregnancy and the onset of hypertensive disorders of pregnancy in women with pre-pregnancy obesity remains unclear. We examined the effects of weight gain during pregnancy on hypertensive disorders of pregnancy among women with pre-pregnancy body mass index (BMI) ≥ 25.0 kg/m2. This multicenter retrospective cohort study included nullipara women who delivered at two units in Japan between 1 January 2013, and 31 December 2020. Singleton primipara (n = 3040) were categorized into two pre-pregnancy BMI groups: 25.0-<30.0, and ≥30.0 kg/m2. Using multiple logistic regression analyses (reported as adjusted odds ratio and 95% confidence interval), gestational weight gain effects on overall hypertensive disorders of pregnancy, gestational hypertension, and pre-eclampsia were determined. Gestational weight gain increased hypertensive disorders of pregnancy (1.09, 1.03-1.16, p < 0.05) and pre-eclampsia risk (1.10, 1.01-1.20, p < 0.05) among the BMI 25.0-<30.0 kg/m2 group and hypertensive disorders of pregnancy risk among the ≥30.0 kg/m2 group (1.07, 1.00-1.05, p < 0.05). Using receiver operating characteristic curve analyses, among the BMI 25.0-<30.0 kg/m2 group, for hypertensive disorders of pregnancy (area under the curve [AUC], 0.63, p < 0.05) and pre-eclampsia (AUC, 0.62; p < 0.05), the weight gain cut-off was 10.5 and 10.6 kg, with sensitivity/specificity of 0.47/0.73 and 0.50/0.73, respectively. For the BMI ≥30.0 kg/m2 group (AUC, 0.63, p < 0.05), the cut-off was 3.5 kg (sensitivity/specificity, 0.75/0.49). The optimal gestational weight gain for reducing hypertensive disorders of pregnancy among women with a pre-pregnancy BMI > 25 kg/m2 may facilitate personalized pre-conception counseling among women with obesity.
Keywords: body mass index; gestational weight gain; hypertensive disorders of pregnancy; obesity; preconception care.