Oral Contraceptives and the Risk of Venous Thrombosis

In the early 1960s, shortly after the introduction of oral contraceptives, the first case reports appeared describing venous thrombosis and pulmonary emboli in women using this method of birth control. Later, myocardial infarction and stroke were also found to be associated with the use of oral contraceptives. These observations led to numerous epidemiologic and clinical studies of oral-contraceptive pills and thrombosis and subsequently to the development of new oral contraceptives with a lower estrogen content. These lower-estrogen contraceptives were considered safer: changes in hemostatic factors remained small, inconsistent in direction, and mostly within the normal range.¹⁴ Recent studies have . . .