We evaluated the impact of adherence to the new Institute of Medicine weight gain guidelines within each prepregnancy body mass index (PPBMI) category on the development of pregnancy-related hypertension (PRH). Patients with singleton term deliveries (≥37 weeks) with documented PPBMI and pregnancy weight gain information were identified from a database of women enrolled for outpatient nursing services. Included were women without history of cardiovascular disease, PRH, or diabetes at initiation of services (N = 7676). Data were stratified by PPBMI (underweight = < 18.5 kg/m(2); normal weight = 18.5 to 24.9 kg/m(2); overweight = 25.0 to 29.9 kg/m(2); obese = ≥ 30.0 kg/m(2)). PRH rates were compared overall and within each PPBMI group for those women gaining less than recommendations, within recommendations, and above recommendations using Pearson's chi-square and Kruskal-Wallis H test statistics. Overall, PRH rates were 5.0%, 5.4%, and 10.8% for less than, within, and above recommendation groups, respectively (P < 0.001). Above recommendation weight gain resulted in higher PRH incidence in each PPBMI category (underweight 7.6%, normal weight 6.2%, overweight 12.4%, and obese 17.0%), reaching statistical significance in all but the underweight PPBMI group. Excessive weight gain above established guidelines was associated with increased rates of PRH. Regardless of PPBMI, women should be counseled to avoid excessive weight gain during pregnancy.
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