Degree of obesity at delivery and risk of preeclampsia with severe features

Abstract

Background: The risk of preeclampsia increases as maternal body mass index (BMI) increases. The link between increasing maternal BMI and preeclampsia with severe features is less well-established.

Objective: To estimate the effect of increasing severity of obesity on risk of preeclampsia with severe features, stratified by early-onset and late-onset disease.

Study design: We performed a retrospective cohort study of consecutive singleton live births at a tertiary care facility from 2004 to 2008. Women were included in the cohort if they delivered a singleton live birth and maternal height and weight was measured on admission. The primary exposure was maternal weight category on presentation for delivery, defined as normal (BMI 18.5-24.9; referent group, n = 1473), overweight (BMI 25-29.9, n = 3081), obese (BMI 30-39.9, n = 4196), and morbidly obese (BMI ≥40, n = 1446). The primary outcome was preeclampsia with severe features. Secondary outcome was early-onset preeclampsia with severe features at <34 weeks or late-onset preeclampsia with severe features at ≥34 weeks. Multivariable logistic regression was used to adjust for confounders.

Results: Of the 10,196 patients meeting inclusion criteria, 1119 developed preeclampsia. Of those, 881 (8.6%) women developed preeclampsia with severe features. Overall, the risk of preeclampsia with severe features was not significantly different in the 4 BMI categories. Of the 10,196 women in the cohort, 1072 delivered <34 weeks and 9124 delivered ≥34 weeks. When stratifying by gestational age at delivery, there was a statistically significant increased risk of developing late-onset preeclampsia with severe features at ≥34 weeks in overweight (4.5%, adjusted odds ratio [aOR] 1.4, 95% confidence interval [CI] 1.0-2.1), obese (6.2%, aOR 2.0, 95% CI 1.4-2.8) and morbidly obese (6.8%, aOR 2.0, 95% CI 1.3-2.9) women compared with normal-weight women (2.9%).

Conclusion: Increasing maternal weight was not associated with preeclampsia with severe features in the total cohort; however, overweight, obese, and morbidly obese women are at increased risk of developing late-onset preeclampsia with severe features.

Keywords: early-onset preeclampsia; late-onset preeclampsia; obesity; preeclampsia with severe features.