A multivariate analysis of risk factors for preeclampsia

Abstract

Objective: --To determine, in a multivariate analysis, risk factors for preeclampsia that could be observed early in pregnancy and to establish whether these risk factors are different for nulliparas and multiparas.

Design: --A case-control study of preeclampsia.

Setting: --Women who gave birth at Northern California Kaiser Permanente Medical Centers in 1984 and 1985.

Participants: --Preeclamptic cases (n = 139) were determined from discharge diagnosis of severe preeclampsia and by confirmation of blood pressures and proteinuria from medical records. Controls (n = 132) were randomly selected women who had no discharge diagnosis of any hypertensive disorder of pregnancy and who had no evidence of hypertension or proteinuria from medical record review.

Main variables examined: --Medical records were abstracted for information regarding maternal age, race, previous pregnancy history, family medical history, socioeconomic status, employment during pregnancy, body mass, and smoking and alcohol consumption.

Results: --Multiple logistic regression analyses confirmed that case patients were more likely than control patients to be nulliparous (adjusted odds ratio [OR], 5.4; 95% confidence interval [Cl], 2.8 to 10.3) and that preeclampsia in a previous pregnancy greatly increased the risk in a subsequent one (adjusted OR, 10.8; 95% Cl, 1.2 to 29.1). However, regardless of parity, preeclamptic women were also more likely to be of high body mass (adjusted OR, 1.7; 95% Cl, 1.2 to 6.2), to work during pregnancy (adjusted OR, 2.1; 95% Cl, 1.1 to 4.4), and to have a family history of hypertension (adjusted OR, 1.7; 95% Cl, 0.92 to 3.2). Having a previous history of a spontaneous abortion was protective but only in multiparous women (adjusted OR for multiparas, 0.09; 95% Cl, 0.02 to 0.48). In contrast, being black was a significant risk for preeclampsia but only in nulliparous women (adjusted OR for nulliparas, 12.3; 95% Cl, 1.6 to 100.8).

Conclusions: --There are a number of risk factors for preeclampsia that may be determined early in a woman's pregnancy. Multiparas and nulliparas share certain risk factors but not others. A cohort investigation is needed to determine the ability of these risk factors to predict who develops preeclampsia.