Thrombosis, or blood clots as they are colloquially known, tend to manifest naturally in men more than women. Women, however, are at risk for blood clots primarily because of pregnancy, birth control, and other hormonal therapies men do not generally take, according to StopTheClot.org.
Birth control pills are the most common form of contraceptive used in the U.S., and carry a high risk of blood clotting. Women who take birth control pills are generally three to four times more likely of developing a blood clot than women who do not take the pill.
It should be noted that the chance of a woman developing a blood clot as a result of taking birth control pills is still relatively small. Only about one in 3,000 women develop a blood clot because of birth control, but if a woman has a history of thrombosis in her family, the risk increases significantly.
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