Hypertensive pregnancy disorders increase the risk of maternal cardiovascular disease after adjustment for cardiovascular risk factors

Abstract

Background and aim: Hypertensive pregnancy disorders are associated with subsequent cardiovascular disease (CVD), but the extent to which this association is explained by shared risk factors is unknown. We aimed to evaluate whether hypertensive pregnancy disorder in first pregnancy is associated with increased subsequent risk of maternal CVD after adjustment for established CVD risk factors measured after pregnancy. Methods and results: A total of 20,075 women with a first delivery registered in the Medical Birth Registry of Norway (1980–2003) participated in Cohort of Norway (CONOR) health surveys a mean (standard deviation) of 10.7 (5.5) years after delivery. They were then followed (median 11.4 years) for an incident fatal or non-fatal CVD event through linkage to the Cardiovascular Disease in Norway (CVDNOR) database and the Norwegian Cause of Death Registry. Hypertensive pregnancy disorders were associated with an increased risk of CVD [Hazard ratio (HR) 2.3; 95% confidence interval (CI) 1.9–2.8], which remained significant after adjustment for established CVD risk factors including body mass index, smoking, hypertension, diabetes, serum glucose and lipid levels (HR 1.5; 95% CI 1.2–1.8). The population attributable fraction of CVD due to hypertensive pregnancy disorder was 4.3% (95% CI 1.9–6.6) after multivariable adjustment. Conclusion: The association between hypertensive pregnancy disorders and CVD risk was mediated in part by related CVD risk factors measured 10 years following delivery. These results underline the importance of post-pregnancy follow-up of women with hypertensive pregnancy disorders focusing on modifiable, lifestyle related risk factors to prevent future CVD.