Epidemiology of oral contraceptives and cardiovascular disease.

PURPOSE: To review the association between combined oral contraceptives and cardiovascular disease, with emphasis on oral contraceptives containing low doses of estrogen (low-dose oral contraceptives). DATA SOURCES: A systematic search of the MEDLINE database was done for all relevant articles published between 1967 (when low-dose oral contraceptives were introduced in the United States) and June 1997. Textbooks, meeting proceedings, and reference lists were also searched. STUDY SELECTION: All English-language human epidemiology studies of oral contraceptives that used cardiovascular disease as an end point were reviewed. Animal and metabolic studies were reviewed only if they were especially relevant to the mechanism of action of oral contraceptives. DATA EXTRACTION: Descriptive and analytic data from each study were collected. DATA SYNTHESIS: Data were organized by cardiovascular end point, study design, estrogen dose, and type of progestogen. Data on relative and absolute risk are presented to address current prescription guidelines.
CONCLUSIONS: The risk for cardiovascular disease is lower with current preparations of oral contraceptives, including those that contain the new progestogens, than with older oral contraceptives containing high doses of estrogen. Among users of low-dose oral contraceptives, cardiovascular diseases occur mainly in smokers and women with predisposing factors. Every effort should be made to encourage smoking cessation among potential users of oral contraceptives.