Progestogens in cardiovascular diseases: an introduction to the epidemiologic data

Earlier publications on the cardiovascular risks associated with oral contraceptive use emphasized the role of estrogens. Today most oral contraceptives contain less tha 50 microgram of estrogen. Furthermore, prescribing practices have improved so that most women with risk factors are not taking oral contraceptives. No differences in risk of fatal myocardial infarctions could be demonstrated by women taking 50 microgram estrogen products versus those taking products with lower estrogen dosages. Perhaps this result reflects small numbers of patients in the study, or perhaps it reflects an effect of progestogen. Since the lower estrogen doses are associated with levonorgestrel, the possibility exists that the advantages of reduced estrogen dosage are masked by the progestogen effect. A larger study is required to examine the relative importance of the estrogen and progestogen components in combined oral contraceptives.