Overview

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). But the risk for DVT or PE is overall very low with hormonal contraceptives.

Birth control pills

In the past, combination birth control pills contained a higher dose of estrogen. The higher dose increased the risk of DVT and PE. Now the combination pill contains a lower dose of estrogen. The risk is reduced. The risk for DVT or PE is actually higher for a pregnant women than for non-pregnant women taking hormonal contraceptives.

Combination hormonal birth control pills that contain the progestin called desogestrel increase the risk of blood clots more than birth control pills that contain other types of progestin.^{footnote 1} The progestin called drospirenone (found in pills such as YAZ or Yasmin) also might have a greater risk of blood clots than other types of progestin.^{footnote 2} Talk to your doctor about the risk of blood clots when deciding which pill is right for you.

Birth control pills are usually stopped within 1 month of major surgery to decrease the risk of a blood clot. The risk needs to be balanced against the risk of an unintended pregnancy by stopping the pills.

The birth control patch

The patch delivers more estrogen than the low-dose birth control pills do. Women who use the patch are slightly more likely to get dangerous blood clots in the legs and lungs than women who use birth control pills. So talk to your doctor about your risks before you use the patch.

Things that can increase your risk for a blood clot

Some of the things that can increase your risk for a blood clot include:

Slowed blood flow

When blood doesn't flow normally, clots are more likely to develop. Reduced blood flow may result from long-term bedrest, such as after a surgery, injury, or serious illness. Or it may result from sitting for a long time, especially when travelling long distances.

Abnormal clotting

Some people have blood that clots too easily or too quickly. Things that may cause increased clotting include:

• Having certain blood problems that make blood clot too easily. This is a problem that may run in families.
• Having certain health problems, such as cancer, heart failure, stroke, or severe infection.
• Being pregnant. The risk of getting blood clots increases both during pregnancy and shortly after delivery or after a caesarean section.
• Using hormonal forms of birth control, gender-affirming hormone therapy, or hormone therapy for menopause.
• Smoking.

Injury to the blood vessel wall

Blood is more likely to clot in veins and arteries shortly after they are injured. Injury can be caused by a recent medical procedure or surgery that involved your legs, hips, belly, or brain. Or it can be caused by an injury, such as a broken hip.