Risk factors differ between recurrent and incident preeclampsia: A hospital-based cohort study

Purpose: To examine whether risk factors, including prepregnancy body mass index (BMI), differ between recurrent and incident preeclampsia. Methods: Data included electronic medical records of nulliparas (n=26,613) delivering 2 times or more in Utah (2002-2010). Modified Poisson regression models were used to examine (1) adjusted relative risks (RR) of preeclampsia and 95% confidence intervals (CI) associated with prepregnancy BMI; (2) maternal risk factor differences between incident and recurrent preeclampsia among primiparous women. Results: In the first pregnancy, compared with normal weight women (BMI: 18.5-24.9), preeclampsia risks for overweight (BMI: 25-29.9), obese class I (BMI: 30-34.9), and obese class II/III (BMI: ≥35) women were 1.82 (95% CI=1.60-2.06), 2.10 (95% CI=1.76-2.50), and 2.84 (95% CI=2.32-3.47), respectively, whereas second pregnancy-incident preeclampsia risks were 1.66 (95% CI=1.27-2.16), 2.31 (95% CI=1.67-3.20), and 4.29 (95% CI=3.16-5.82), respectively. Recurrent preeclampsia risks associated with BMI were highest among obese class I women (RR=1.60; 95% CI=1.06-2.42) without increasing in a dose-response manner. Nonwhite women had higher recurrence risk than white women (RR=1.70; 95% CI=1.16-2.50), whereas second pregnancy-incident preeclampsia risk did not differ by race. Conclusion: Prepregnancy BMI appeared to have stronger associations with risk of incident preeclampsia either in the first or second pregnancy, than with recurrence risk. Nonwhite women had higher recurrence risk.