Time to onset of cardiovascular and cerebrovascular outcomes after hypertensive disorders of pregnancy: a nationwide, population-based retrospective cohort study

Abstract

Background: The increased maternal cardiocerebrovascular risk after a pregnancy complicated by hypertensive disorders of pregnancy, is well documented in the literature. Recent evidence has suggested a shorter timeframe for the development of these postnatal outcomes, which could have major clinical implications.

Objective: This study aimed to determine the risk of and time to onset of maternal cardiovascular and cerebrovascular outcomes after a pregnancy complicated by hypertensive disorders of pregnancy.

Study design: This study included 2,227,711 women, without preexisting chronic hypertension, who delivered during the period 2008 to 2010: 37,043 (1.66%) were diagnosed with preeclampsia, 34,220 (1.54%) were diagnosed with gestational hypertension, and 2,156,448 had normotensive pregnancies. Hospitalizations for chronic hypertension, heart failure, coronary heart disease, cerebrovascular disease, and peripheral arterial disease were studied. A classical Cox regression was performed to estimate the average effect of hypertensive disorders of pregnancy over 10 years compared with normotensive pregnancy; moreover, an extended Cox regression was performed with a step function model to estimate the effect of the exposure variable in different time intervals: <1, 1 to 3, 3 to 5, and 5 to 10 years of follow-up.

Results: The risk of chronic hypertension after a pregnancy complicated by preeclampsia was 18 times higher in the first year (adjusted hazard ratio, 18.531; 95% confidence interval, 16.520-20.787) to only 5 times higher at 5 to 10 years after birth (adjusted hazard ratio, 4.921; 95% confidence interval, 4.640-5.218). The corresponding risks of women with gestational hypertension were 12 times higher (adjusted hazard ratio, 11.727; 95% confidence interval, 10.257-13.409]) and 6 times higher (adjusted hazard ratio, 5.854; 95% confidence interval, 5.550-6.176), respectively. For other cardiovascular and cerebrovascular outcomes, there was also a significant effect with preeclampsia (heart failure: adjusted hazard ratio, 6.662 [95% confidence interval, 4.547-9.762]; coronary heart disease: adjusted hazard ratio, 3.083 [95% confidence interval, 1.626-5.844]; cerebrovascular disease: adjusted hazard ratio, 3.567 [95% confidence interval, 2.600-4.893]; peripheral arterial disease: adjusted hazard ratio, 4.802 [95% confidence interval, 2.072-11.132]) compared with gestational hypertension in the first year of follow-up. A dose-response effect was evident for the severity of preeclampsia with the averaged 10-year adjusted hazard ratios for developing chronic hypertension after early, preterm, and late preeclampsia being 10, 7, and 6 times higher, respectively.

Conclusion: The risks of cardiovascular and cerebrovascular outcomes were the highest in the first year after a birth complicated by hypertensive disorders of pregnancy. We found a significant relationship with both the severity of hypertensive disorders of pregnancy and the gestational age of onset suggesting a possible dose-response relationship for the development of cardiovascular and cerebrovascular outcomes. These findings call for an urgent focus on research into effective postnatal screening and cardiocerebrovascular risk prevention for women with hypertensive disorders of pregnancy.

Keywords: cardiovascular complications; cerebrovascular complications; chronic hypertension; gestational hypertension; hazard ratio; hypertensive disorders; medicoadministrative database; preeclampsia; pregnancy.