3RD-GENERATION ORAL-CONTRACEPTIVE AND DEEP VENOUS THROMBOSIS - FROM EPIDEMIOLOGIC CONTROVERSY TO NEW INSIGHT IN COAGULATION

Four epidemiologic studies showed a twofold increase in risk of deep v enous thrombosis with the use of oral contraceptives containing third- generation progestins, relative to second-generation products. These f indings have been strongly debated ever since, and new studies have be en added. In the current article we examine whether the findings can b e explained by potential biases or other shortcomings of the epidemiol ogic studies. We conclude that complete certainty cannot exist but tha t the most rational conclusion from the epidemiologic findings and the ir discussion is that an increased risk of deep venous thrombosis with third-generation contraceptives is likely, especially in first-time a nd young users. The controversy has recently led to new insights in co agulation: Women who use third-generation contraceptives acquire a res istance to the blood's own anticoagulation system, similar to the acti vated protein C resistance that is seen in persons who carry the facto r V Leiden mutation but different from that in women using second-gene ration contraceptives.