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

BACKGROUND: The increased maternal cardio-cerebro-vascular risk after hypertensive disorders of pregnancy (HDP) is well documented in the literature. Recent evidence has suggested a shorter time frame for the development of these postnatal outcomes, which could have major clinical implications.

OBJECTIVE(S): To determine the risk of and time to onset of maternal cardiovascular and cerebrovascular outcomes (CVO) after hypertensive disorder of pregnancy (HDP).

STUDY DESIGN: We included 2,227,711 women, without pre-existing chronic hypertension, who delivered during the period 2008-2010: 37,043 were diagnosed with pre-eclampsia (PE:1.66%), 34,220 with gestational hypertension (GH:1.54%) and 2,156,448 were normotensive pregnancies. Hospitalizations for chronic hypertension, heart failure, coronary heart, cerebrovascular and peripheral arterial diseases were studied. We performed a classical Cox regression to estimate the average effect of HDP over 10 years compared to normotensive pregnancy but also an extended Cox regression with Step Function model in order to estimate the effect of the exposure variable in different time intervals: <1 year, 1-3, 3-5, and 5-10 years of follow-up.

RESULTS: The risk of chronic hypertension after PE was 18-times higher in the first year (aHR=18.531[16.520-20.787]) to only 5-times higher at 5 to 10 years following birth (aHR=4.921[4.640-5.218]). The corresponding risks for women with GH was 12-times higher (aHR=11.727[10.257-13.409]) and 6-times higher (aHR=5.854[5.550-6.176]), respectively. For other cardiovascular and cerebrovascular outcomes, there was also a significant effect with PE (heart failure aHR=6.662[4.547-9.762], coronary heart disease 3.083[1.626-5.844], cerebrovascular disease 3.567[2.600-4.893], peripheral arterial disease 4.802[2.072-11.132]) as for GH in the first year of follow-up. A dose response effect was evident for severity of PE with the averaged 10-year aHRs for developing chronic hypertension after early, preterm and late PE being 10-, 7- and 6-times higher, respectively.

CONCLUSIONS: The risks of CVO were highest in the first year following an HDP birth. We found a significant relationship with both the severity of HDP and the gestational age of onset suggesting a possible dose-response relationship for the development of CVO. These findings call for an urgent focus on research into effective postnatal screening and cardio/cerebro-vascular prevention for women who have HDP.