Super-obesity and risk for early and late pre-eclampsia AK Mbah, a,b JL Kornosky, c S Kristensen, d EM August, a,b AP Alio, a,b PJ Marty, a V Belogolovkin, e K Bruder, e HM Salihu a,c a Center for Research and Evaluation, The Chiles Center, University of South Florida, Tampa, FL, USA b Department of Community and Family Health, University of South Florida, Tampa, FL, USA c Department of Epidemiology and Biostatistics, University of South Florida, Tampa, FL, USA d Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL, USA e Department of Obstetrics and Gynecology, Division of Maternal–Fetal Medicine, University of South Florida, Tampa, FL, USA Correspondence: Dr HM Salihu, Center for Research and Evaluation, Lawton and Rhea Chiles Center for Healthy Mothers and Babies, University of South Florida, 3111 E. Fletcher Avenue, Tampa, FL 33613, USA. Email hsalihu@health.usf.edu Accepted 9 April 2010. Published Online 19 May 2010. Objective To examine the association between obesity subtypes and risk of early and late pre-eclampsia. Design Population-based retrospective study. Setting State of Missouri maternally linked birth cohort files. Population All singleton live births in the state of Missouri from 1989 to 2005. Methods The body mass index (BMI) was used to classify women as normal weight (BMI = 18.5–24.9 kg/m 2 ), class I obesity (BMI = 30–34.9 kg/m 2 ), class II obesity (BMI = 35–39.9 kg/m 2 ), class III obesity (BMI = 40–49.9 kg/m 2 ) or super-obesity (BMI ‡ 50 kg/m 2 ). Adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association between obesity and the risk of pre-eclampsia were obtained from logistic regression models with adjustment for intracluster correlation. Results The rate of pre-eclampsia increased with increasing BMI, with super-obese women having the highest incidence (13.4%). Compared with normal weight women, obese women (BMI ‡ 30 kg/m 2 ) had a higher risk for pre-eclampsia (OR = 2.59, 95% CI = 2.87–3.01). This risk remained approximately the same for late-onset pre-eclampsia (pre- eclampsia occurring at 34 weeks or more of gestation) and was slightly reduced for early-onset pre-eclampsia (pre-eclampsia occurring at 34 weeks or less of gestation). Within each BMI category, the risk of pre-eclampsia increased with the rate of weight gain. Compared with normal weight mothers with moderate weight gain, super-obese women with a high rate of weight gain had the greatest risk for pre-eclampsia (OR = 7.52, 95% CI = 2.70–21.0). Conclusion BMI and rate of weight gain are synergistic risk factors that amplify the burden of pre-eclampsia among super-obese women. Keywords Pre-eclampsia, pregnancy, super-obesity, weight gain. Please cite this paper as: Mbah A, Kornosky J, Kristensen S, August E, Alio A, Marty P, Belogolovkin V, Bruder K, Salihu H. Super-obesity and risk for early and late pre-eclampsia. BJOG 2010;117:997–1004. Introduction Pre-eclampsia affects about 2–8% of pregnancies worldwide and has a negative impact on maternal and neonatal mor- bidity and mortality. 1,2 Several studies have identified maternal pre-pregnancy body mass index (BMI) as an important risk factor for pre-eclampsia, noting possible dif- ferences in the aetiologies of early and late pre-eclampsia, with the former generally being regarded as more severe in terms of maternal and fetal outcomes. 2–4 However, not all studies have examined the relationship between BMI and the incidence of early and late pre-eclampsia independently. Furthermore, different classifications of pre-eclampsia have been used in previous studies, rendering comparisons difficult. 5,6 Another important consideration in the current wave of the obesity epidemic is the disproportional increase in the rate of obesity by obesity subtypes. For example, it has been shown that, over the previous two decades, the pro- portion of ‘super-obese’ individuals (BMI ‡ 50 kg/m 2 ) has quintupled. 7 The term ‘super-obesity’ was first coined in 1987 to describe a special category of patients with BMI ‡ 50 kg/m 2 undergoing surgical treatment as a result of the high rates of co-morbidity (hypertension, diabetes, ª 2010 The Authors Journal compilation ª RCOG 2010 BJOG An International Journal of Obstetrics and Gynaecology 997 DOI: 10.1111/j.1471-0528.2010.02593.x www.bjog.org Epidemiology