Excessive weight gain and hypertensive disorders of pregnancy in the obese patient

Objective: To evaluate the association between excessive weight gain and pregnancy-related hypertension (PRH) among obese women (body mass index (BMI) >= 30 kg/m(2)). Methods: We performed a case control study among women with (n=440) and without (n=600) PRH from 2005 to 2007. Height and weight were recorded at initial and final prenatal visits. 695 women had BMI recorded at <18 weeks of gestation, of which 257 (36.9%) were obese. Obese women were divided into three categories based on 2009 Institute of Medicine (IOM) guidelines: (1) below recommended amount (under weight gain UWG); (2) more than recommended (excessive weight gain - EWG) or (3) within recommended amount (normal weight gain - NWG). PRH was defined as gestational hypertension, mild or severe preeclampsia. Patients with and without PRH were prospectively identified. The association between weight gain category and development of PRH was analyzed. Results: We noticed a 1.5-fold higher odds of having PRH with an initial BMI >= 30 kg/m(2) compared to BMI <30 kg/m(2) (OR 1.64, 95% Cl 1.2-2.2, p = 0.002). Among obese women, we noted a 2-fold higher odds of having PRH with EWG compared to NWG (OR 2.52, 95% Cl 1.2-3.9, p = 0.012). The increased odds persisted after adjusting for race, chronic hypertension and diabetes, and length of gestation (AOR 2.61, 95% Cl 1.4-4.9, p = 0.003). Among obese women with PRH, those with EWG had a 76% decreased odds of having severe disease compared to NWG (OR = 0.242 [0.07-0.79], p = 0.019). Conclusion: We have demonstrated that EWG among obese patients increases overall risk of PRH.