Past use of oral contraceptives and cardiovascular disease: a meta-analysis in the context of the Nurses' Health Study.

We examined the effects of past use of oral contraceptives on risks of cardiovascular diseases prospectively in the Nurses' Health Study cohort. The 119,061 participants were 30 to 55 years old and free of coronary disease or stroke in 1976. They provided information on biennial questionnaires and were followed for 8 years. There were 380 nonfatal myocardial infarctions and 105 deaths from coronary disease, 282 strokes, and 48 other cardiovascular deaths. We observed virtually no differences in the rates of various cardiovascular diseases between never and past users of oral contraceptives, regardless of duration of use or time since last use. For major coronary disease, the relative risk was 0.8 (95% confidence intervals, 0.6 to 1.0). A quantitative meta-analysis of 13 studies yielded an estimated relative risk of 1.01 (95% confidence intervals, 0.91 to 1.13) for coronary heart disease. Past use of oral contraceptives has little or no impact on risks of subsequent cardiovascular diseases.