Risk Factors for Eclampsia: A Population-based Study in Washington State, 1987–2007: Coghill AE, Hansen S, Littman AJ. Am J Obstet Gynecol 2011;205:553.e1–7.

Abstract

Eclampsia is defined as generalized seizure with or without coma (in the absence of other neurologic conditions) with the concomitant onset of hypertension and proteinuria at>20 weeks gestation. Estimates of the incidence for eclampsia vary widely from 1 in 100 to 1 in 4000. The authors of this study evaluated all women with singleton births in Washington State from 1987–2007 through the state's Birth Events Reporting System in an effort to update the previous characterizations of risk factors for eclampsia, taking into account shifts in population demographics (specifically, increased obesity) and to evaluate a more heterogeneous population than prior studies. There were 781 women discharged with a diagnosis of eclampsia during this time period. They were matched with 3124 controls randomly selected from those discharged without a diagnosis of eclampsia. Multivariable logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Nearly 50% of cases and controls were missing data for key variables such as body mass index (BMI) and level of education. As such, multiple imputation procedures were performed to address missing data. Results were provided as ORs, first without multiple imputation data, then with these data. Risk of eclampsia was greater in nulliparous, compared to parous, women (OR 3.04, 95% CI 2.20–4.19; OR 3.06, 95% CI 2.43–3.87). Being a young mother and an older mother were each associated with elevated risk (age<20 years: OR 1.87, 95% CI 1.29–2.71; OR 2.08, 95% CI 1.61–2.69; age>35 years: OR 1.69, 95% CI 1.13–2.53; OR 1.45, 95% CI 1.07–1.96). Longer birth interval (> 5 years: OR 1.92, 95% CI 1.09–3.37; OR 1.63, 95% CI 1.08–2.46), low socioeconomic status (OR 1.18, 95% CI 0.88–1.59; OR 1.23, 95% CI 1.00–1.49), gestational diabetes (OR 1.79, 95% CI 1.06–3.02; OR 1.72, 95% CI 1.13–2.63), pre-pregnancy obesity (BMI > 30: OR 1.73, 95% CI 1.26–2.37; 1.41, 95% CI 1.09–1.83), and weight gain during pregnancy above or below recommended guidelines (< 25 lb: OR 1.47, 95% CI 1.04–2.07; OR 1.23, 95% CI 0.95–1.61;>35 lb: 1.68, 95% CI 1.23–2.30; OR 1.39, 95% CI 1.09–1.78) were positively associated with eclampsia. Multiparity and smoking were negatively associated with risk. This study confirmed previously known risk factors (maternal age and parity) for eclampsia and identified new risk factors such as presence of gestational diabetes and BMI>30.