Risk factors

A family history of factor V Leiden increases your risk of inheriting the disorder. The disorder is most common in people who are white and of European descent.

People who have inherited factor V Leiden from only one parent have a 5 percent chance of developing an abnormal blood clot by age 65. Factors that increase this risk include:

• Two faulty genes. Inheriting the genetic mutation from both parents instead of just one can significantly increase your risk of abnormal blood clots.
• Immobility. Extended periods of immobility, such as sitting during a long airplane flight, can increase the risk of leg clots.
• Estrogens. Oral contraceptives, hormone replacement therapy and pregnancy can make you more likely to develop blood clots.
• Surgeries or injuries. Surgeries or injuries such as broken bones can increase your risk of abnormal blood clots.
• Non-O blood type. Abnormal blood clots are more common in people who have blood types of A, B or AB compared with those with blood type O.