Contraceptives and Thrombosis: An Intertwined Revolutionary Road.

The development of oral contraceptives (OCs) began in 1921 and continued in the following years until the first regulatory approval from the Food and Drug Administration was granted in 1960. However, it took several years to realize that OCs presented an important but not frequent risk of venous thrombosis. Several reports ignored this dangerous effect and only in 1967 the Medical Research Council clearly stated this as an important risk. Later, research led to the formulation of second-generation OCs containing progestins, which nevertheless presented an increased thrombotic risk. In early 1980s, OCs containing third-generation progestins were introduced into the market. Only in 1995, it became clear that these new compounds induced a higher thrombotic risk than that related to the second-generation progestins. It appeared clear that the modulating action of progestins was against the procoagulant activity of estrogens. Lastly, at the end of the 2000s, OCs containing natural estrogens and a fourth-generation progestin (dienogest) became available. The prothrombotic effect of those natural products was not different from that of preparations containing second-generation progestins. Moreover, research over the years has produced much data on risk factors associated with OCs use such as age, obesity, cigarette smoking, and thrombophilia. These findings allowed us to better assess the individual thrombotic risk (both arterial and thrombotic) of each woman before offering an OC. Furthermore, research has shown that in high-risk people the use of single progestin is not dangerous as far as thrombosis is concerned. In conclusion, the OCs road has been long and difficult but has led to a great and unthinkable scientific and social enrichment since the 1960s.