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Hypertension in pregnancy and risk of coronary heart disease and stroke: A prospective study in a large UK cohort.

Canoy D, Cairns BJ, Balkwill A, Wright FL, Khalil A, Beral V, Green J, Reeves G; Million Women Study Collaborators.

Int J Cardiol 2016;222:1012-1018.

Many studies investigating long-term vascular disease risk associated with hypertensive pregnancies examined risks in relatively young women among whom vascular disease is uncommon. We examined the prospective relation between a history of hypertension during pregnancy and coronary heart disease (CHD) and stroke in middle-aged UK women.

In 1996-2001, 1.1 million parous women (mean age=56years) without vascular disease at baseline reported their history of hypertension during pregnancy and other factors. They were followed for incident CHD and stroke (hospitalisation or death). Adjusted relative risks (RRs) were calculated using Cox regression.

Twenty-six percent (290,008/1.1 million) reported having had a hypertensive pregnancy; 27% (79,163/290,008) of women with hypertensive pregnancy, but only 10% (82,145/815,560) of those without hypertensive pregnancy, reported being treated for hypertension at baseline. Mean follow-up was 11.6years (mean ages at diagnosis/N of events: CHD=65years/N=68,161, ischaemic stroke=67years/N=8365, haemorrhagic stroke=64years/N=5702). Overall, the RRs (95% confidence interval [CI]) of incident disease in women with hypertensive pregnancy versus those without such history were: CHD=1.29 (1.27-1.31), ischaemic stroke=1.29 (1.23-1.35), and haemorrhagic stroke=1.14 (1.07-1.21). However, among women with hypertensive pregnancy who were not taking hypertension treatment at baseline, their RRs (95% CI) were only modestly increased: CHD=1.17 (1.14-1.19), ischaemic stroke=1.18 (1.11-1.25), and haemorrhagic stroke=1.09 (1.02-1.18).

Hypertension during pregnancy was associated with increased CHD and stroke incidence in middle age, largely because such women also had hypertension in their 50s and 60s, which has a substantially greater effect on vascular disease risk than hypertension during pregnancy without hypertension later in life.