Case-Control Study of the Risk Factors for Eclampsia

A case-control study was conducted to investigate risk factors for eclampsia. A total of 66 cases of eclampsia were ascertained from deliveries between 1977 and 1992 at two hospitals in Houston, Texas, based on the criteria defined by the American College of Obstetrics and Gynecology. Cases were matched to nonpreeclamptic controls on a 4:1 ratio on the basis of hospital and month of delivery. The ratio of eclampsia cases to number of deliveries over the study period was 0.63 per 1,000. In a logistic regression model, risk factors for eclampsia included 1) two or fewer prenatal care visits (odds ratio (OR) = 6.10, 95% confidence interval (CI) 2.26-16.41), 2) urinary tract infection (OR = 4.23, 95% CI 1.27-14.06), 3) primigravidity (OR = 2.87, 95% CI 0.97-8.44), 4) obesity (OR = 2.49, 95% CI 0.78-7.96), 5) black ethnicity (OR = 2.25, 95% CI 0.88-5.78), 6) history of diabetes (OR = 2.07, 95% CI 0.45-9.62), and 7) age < or = 20 years (OR = 1.55, 95% CI 0.47-5.10). Nulliparity was not shown to be a risk factor for eclampsia when controlled for primigravidity, and neither were previous history of abortion or previous history of pregnancy-induced hypertension. Thus, prior pregnancy itself, independent of outcome and preeclamptic/eclamptic complications, appears to be the protective factor against eclampsia in a subsequent pregnancy.