A COHORT STUDY OF EPIDEMIOLOGIC ASSOCIATIONS AND OUTCOMES OF PREGNANCIES WITH HYPERTENSIVE DISORDERS

Objective: To determine the associations of maternal biological and so ciodemographic characteristics with different types of hypertensive di sorders of pregnancy, their incidence, and the outcomes of the pregnan cies. Method: A prospectively collected birth cohort of 9247 singleton pregnancies from the northernmost provinces of Finland with the expec ted date of delivery falling between July 1, 1985 and June 30, 1986. R esults: The total number of women with elevated blood pressure was 179 3 (17.2%). The incidence of chronic hypertension was 4.3%, that of ges tational hypertension 11.0%, and that of preeclampsia 1.9%. Advanced m aternal age and high prepregnancy body weight were associated with an increased risk of chronic hypertension in parous women and of gestatio nal hypertension and preeclampsia in nulliparous women. A risk of pree clampsia also arose from low education and employment during pregnancy . The occurrence of all hypertensive complications was lower among smo kers than nonsmokers. Previous abortions had a slight, but nonsignific ant, protective effect, and the method of contraception had no influen ce on the prevalence of preeclampsia among the primiparous women. A se asonal trend in the prevalence of preeclampsia was observed, with a pe ak in April. The highest perinatal mortality was associated with chron ic hypertension (2.8% CI 1.6-5.0), regardless of superimposed preeclam psia, whereas gestational hypertension increased maternal and perinata l morbidity but not mortality. Preeclampsia was related to the highest rates of maternal complications and perinatal morbidity especially pr ematurity, SGA, and need of neonatal intensive care (28%). Conclusions : Certain maternal characteristics, such as advanced maternal age, nul liparity, obesity, low education, employment and chronic hypertension, are associated with hypertensive disorders during pregnancy and are k nown at the first visit to health care, Attention to the risk factors can enable supervision of the pregnancy with the aim of early detectio n of hypertension and its complications.