Hormonal Birth Control: Risk of Blood Clots In some women, the
estrogen in combination hormonal birth control methods increases
the risk of a blood clot in a leg (deep vein thrombosis, or DVT)
or a blood clot in a lung (pulmonary embolism, or PE). A blood
clot in a leg vein can travel through the circulation system and
cause pulmonary embolism. The risk for DVT or PE is overall very
low with hormonal contraceptives. In the past, combination birth
control pills contained a higher dose of estrogen, which
increased the risk of DVT and PE. Now the combination pill
contains a lower dose of estrogen, and the risk is reduced. The
risk for DVT or PE is actually higher for a pregnant women than
for nonpregnant women taking hormonal contraceptives.
Combination hormonal contraceptives that contain the progestin
called desogestrel increase the risk of DVT or PE more than
contraceptives that contain other types of progestin. The birth
control patch delivers more estrogen than the low-dose birth
control pills do. The U.S.