Your Resource for all Things Relating to Factor V Leiden

Factor V Leiden and Birth Control

There are more than 60 million women of child-bearing age in the United States, and the majority of them report using some form of birth control. Birth control pills (also known as an oral contraceptives) are the leading method of birth control used followed by the patch and the ring. The pill, the patch, or the ring when they contain estrogen all do the same thing. They cause the body to hormonally imitate pregnancy, or to think it’s pregnant. In doing so, they prevent pregnancy.


Most oral contraceptives contain an estrogen and a progestin (synthetic progesterone). Estrogen and progesterone have many effects on a woman’s body. They are the hormones that sustain pregnancy and, when given in the form of birth control pills, imitate pregnancy, thereby preventing pregnancy. These hormones also increase the levels of clotting factors so that their blood will clot more readily and protect them from any bleeding challenge that might occur with a miscarriage or during childbirth. When birth control methods made with pregnancy hormones like estrogen and progestin cause the body to think that it’s pregnant, these same changes will occur, putting women at an increased risk for blood clots.

While research shows that birth control pills are safe and effective, just like any other medication, they can pose some risks. One risk associated with any form of hormonal birth control that contains estrogen, including the pill, patch, or ring, is a life-threatening blood clot.


The birth control pill, the patch and the ring do not directly cause blood clots, but they do increase the risk that a woman might experience a blood clot.

What are the risks of getting a blood clot while using birth control containing estrogen?

The use of birth control pills with estrogen increases a woman’s risk for blood clots by about three to four times compared to a woman not using birth control pills. Some of the newer birth control pills women use pose a risk two-times greater than older birth control pills. The use of patches and rings containing estrogen poses a risk double that of birth control pills. Injectable progestin (DMPA) may increase blood clotting risk up to two-fold as well.


Women with a clotting disorder such as Factor V Leiden, a previous blood clot, or a family history of blood clots are at an even greater risk.

What are the risks of getting a blood clot while using birth control containing estrogen if I have Factor V Leiden?

The risk for developing a blood clot in a vein (called a venous thromboembolism or VTE) as a result of taking oral contraceptives has been known since the early 1960’s and has remained a topic of debate.


For the average woman taking birth control pills, the absolute risk of a blood clot is small. Only 1 in 300 women per year who are taking birth control pills will develop such a clot. For a woman with an inherited blood clotting disorder like Factor V Leiden or a history of thrombosis (blood clots), however, this risk is significantly higher.


According to a study from 2015, the estimated relative risk for developing a venous blood clot or VTE in patients with Factor V Leiden who are also taking oral contraceptives has been reported to be 10-30 times greater in heterozygous patients (those with one mutated factor V gene) and up to 80-100 times greater in patients who are homozygous (those with two mutated factor V genes) compared to women who do not have Factor V Leiden and do not take oral contraceptives. Some studies have determined that the risk could be as high as 35-50 times greater for heterozygous Factor V Leiden patients and several hundred times greater for homozygous patients. The risk also appears to be even greater when using third generation oral contraceptives specifically (i.e., oral contraceptives that contain desogestrel, gestodene, or norgestimate as the progestin). 


In addition to the common venous blood clots most often seen in VTE patients such as a deep vein thrombosis (DVT) and pulmonary embolism (PE), patients with Factor V Leiden who use oral contraceptives are at a 20-fold greater risk for developing a cerebral vein thrombosis (venous blood clots in the brain).


The new patches (transdermal contraceptives) may increase the above potential risks even more. The amount of estrogen absorbed from the patches has been reported to be 60 percent higher than the amount delivered by the pills. Little information about the risk of blood clots with birth control rings is available. Like patches and most birth control pills, the birth control rings also contain an estrogen and a progestin; thus they probably carry a risk of thrombosis similar to that of birth control pills or patches.


Women should take control of their health and carefully evaluate these potential risks when considering birth control options.

How can I reduce my risk?

Whether you have a clotting disorder or not, you can plan your family as you choose. There are safe alternatives if you want to avoid the increased risk of blood clots associated with birth control methods that contain estrogen. Several of these options include:


  • Barrier methods
  • Spermicides
  • Progestin implant
  • Copper IUD
  • Progestin IUD
  • Progestin-only pills, which studies show do not increase the risk for blood clots
  • Tubal ligation or vasectomy for their partner

Where can I find more information about birth control options?

Soon you will be able to visit our Research and Resource Library to obtain very in-depth information about Factor V Leiden and how it relates to birth control and blood clots. We will share with you the latest research and recommendations from the best professionals in their field.

In the meantime, the National Blood Clot Alliance (NBCA), working with the Alexandra L. Rowan Memorial Foundation, has put together some excellent resources to provide women with life-saving information about birth control and blood clots, and to help them determine, along with their doctor, their risk for blood clots and all of their birth control options. To access these resources, click on the links below:

To Learn More About Women & Blood Clots...

Each year, up to 900,000 people are affected by blood clots, and about 100,000 people will die because of blood clots. However, many of these deaths can be prevented simply by sharing life-saving information. To learn more about women and blood clot risks, signs and symptoms, and prevention, please visit and share

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