Does a history of hypertensive disorders of pregnancy help predict future essential hypertension? Findings from a prospective pregnancy cohort study.

Hypertensive disorder of pregnancy (HDP) is considered an important determinant in the prediction of future hypertension. The aim of this study is to examine whether HDP improves prediction of future hypertension, over prediction based on established risk factors measured during pregnancy. We used a community based cohort study of 2117 women who received antenatal care at a major hospital in Brisbane between 1981 and 1983 and had blood pressure assessed 21 years after the index pregnancy. Of these 2117 women, 193 (9.0%) experienced HDP and 345 (16.3%) had hypertension at 21 years postpartum. For women with HDP, the odds of being hypertensive at 21 years postpartum were 2.46 (95% CI 1.70, 3.56), adjusted for established risk factors including age, education, race, alcohol, cigarettes, exercise and body mass index. Addition of HDP did not improve the prediction model that included these established risk factors, with the area under the curve of receiver operator (AUROC) increasing from 0.710 to 0.716 (P-value for difference in AUROC=0.185). Our findings suggest that HDP is strongly and independently associated with future hypertension, and women who experience this condition should be counselled regarding lifestyle modification and careful ongoing blood pressure monitoring. However, the development of HDP during pregnancy does not improve our capacity to predict future hypertension, over risk factors identifiable at the time of pregnancy. This suggests that counseling regarding lifestyle modification and ongoing blood pressure monitoring might reasonably be provided to all pregnant and postpartum women with identifiable risk factors for future hypertension.