COMPARISON OF RISK-FACTORS FOR PREECLAMPSIA AND GESTATIONAL HYPERTENSION IN A POPULATION-BASED COHORT STUDY

The objective of this study was to evaluate and compare risk factor pa tterns in association with preeclampsia and gestational hypertension. The data were collected from The Swedish Medical Birth Register and in clude all nulliparas aged 34 years or less who gave birth at the Unive rsity Hospital of Uppsala, Sweden, during 1987-1993. Of these 10,666 w omen, 4.4% developed gestational hypertension, and 5.2% developed pree clampsia. The following risk factors were significantly associated wit h increased risk of preeclampsia: type 1 diabetes (odds ratio = 5.58, 95% confidence interval 2.72-11.43), gestational diabetes (odds ratio = 3.11, 95% confidence interval 1.61-6.00), and twin birth (odds ratio = 4.17, 95% confidence interval 2.30-7.55). The positive associations between these variables and the risk of gestational hypertension were weaker and nonsignificant. Compared with underweight women (body mass index < 19.8), obese women (body mass index > 29) had increased risks of both gestational hypertension (odds ratio = 4.85, 95% confidence i nterval 1.97-11.92) and preeclampsia (odds ratio = 5.19, 95% confidenc e interval 2.35-11.48). Significantly lower risks of preeclampsia and gestational hypertension were observed for women born outside Nordic c ountries and in association with maternal smoking and summer birth. Th e similarities in risk factor patterns may indicate similarities in th e biologic mechanisms underlying the two conditions.