Cardiovascular death in women who had hypertension in pregnancy: a case–control study

OBJECTIVE: To determine whether an association exists between hypertension in pregnancy and later development of cardiovascular disease. DESIGN: Case-control study of women who delivered with and without hypertensive complications during the same period. SETTING: University Hospital in Reykjavik, Iceland. POPULATION: Three hundred and twenty-five women with hypertension in pregnancy (blood pressure > or =140/90 mmHg after 20 weeks of gestation) in the years 1931-1947, graded by severity. For each case, two normotensive control women, delivering before or after the case and matched for parity and age were selected, giving a total of 629 women. METHODS: Causes of death were evaluated for the presence of ischaemic heart disease, cerebrovascular events and cancer, up until the end of 1996. MAIN OUTCOME MEASURES: Survival curves, median survival times, risk of death by age group and severity of disease. RESULTS: Death with evidence of ischaemic heart disease was more common in cases (24.3%) than in control women (14.6%) (RR 1.66; 95% CI 1.27-2.17). Cerebrovascular event deaths occurred in 9.5% of cases and in 6.5% of controls (RR 1.46; 95% CI 0.94-2.28). Cancer death rates were not different (RR 1.22; 95% CI 0.91-1.63). Survival times were shorter on average by three to nine years as a consequence of cardiovascular disease. This varied by age group in the index pregnancy for women with a history of hypertension in pregnancy. The effect was smaller if the case pregnancy occurred at a young age. There was a linear trend with increasing severity of hypertensive disease in pregnancy in death rates from ischaemic heart disease (chi(2) (1)= 5.8, P= 0.02). CONCLUSIONS: Long term follow up suggests an increased risk of death from ischaemic heart disease and cerebrovascular events among women who suffered hypertension in pregnancy.