32 Predictors of persistent hypertension after pregnancies with hypertensive disorders of pregnancy

Abstract

Introduction Hypertensive disorders of pregnancy (HDP) occur in 6–10% of all pregnancies. A significant proportion of previously normotensive women persist with elevated blood pressure 12 weeks postpartum. Investigation on factors involved in the persistence of hypertension is of critical importance to provide quality health care for those women. The aim of our study is to identify factors involved in the persistence of hypertension at 12 weeks after pregnancies complicated by HDP. Methods We conducted a case-control study nested in a prospective cohort of outpatient women who had HDP at a teaching hospital in Porto Alegre, RS. At first visit, all women informed socio-demographic characteristics, medical and pregnancy histories. At follow-up visits we collected information on use of antihypertensive medication, blood pressure, urinary and serum analysis. Results We selected 99 women in the cohort with no pre-existing hypertension and that were followed until 12 weeks postpartum. Hypertensive women after 12 weeks from delivery were considered cases (n = 56) and normotensive women after 12 weeks were labelled controls (n = 43). We developed a risk prediction model with independent variables for persistent hypertension after pregnancy. Our results showed that both blood pressure and use of antihypertensive medication were significantly different at first visit. Mean systolic and diastolic blood pressure were, respectively, 138.6 (20.6) mmHg and 91.9 (12.3) mmHg for the hypertensive group and 117.9 (12) mmHg and 78.4 (8.9) mmHg for controls (p 0.001). Maternal age was significantly higher in the hypertensive group. Gestational outcomes and biochemical parameters were similar between groups. Gestational age at delivery, maternal age and both systolic and diastolic blood pressures at first visit were independent variables chosen to compose a risk model with an area under the ROC of 0.896 (95% CI 0.819-0.972) to predict persistent hypertension after pregnancy. Conclusion Gestational age at delivery, maternal age and blood pressure were identified as important factors involved in persistent hypertension 12 weeks after pregnancies complicated by HDP. We believe that prospective studies with larger population are needed to access the value of a risk model to predict, at first visit postpartum, which women have increased chance to become chronically hypertensive.