Factor V Leiden thrombophilia is an inherited disorder of blood clotting. Factor V Leiden is the name of a specific mutation that results in thrombophilia, or an increased tendency to form abnormal blood clots in blood vessels. People who have the factor V Leiden mutation are at somewhat higher than average risk for a type of clot that forms in veins, such as the deep veins of the legs (deep venous thrombosis), or a clot that travels through the bloodstream and lodges in the lungs (pulmonary embolism). Most people with the factor V Leiden mutation never develop abnormal blood clots, however.

The factor V Leiden mutation is associated with a somewhat increased risk of pregnancy loss (miscarriage), and some research suggests that it may also increase the risk of other complications during pregnancy. These complications may include pregnancy-induced high blood pressure (pre-eclampsia), slow fetal growth, and early separation of the placenta from the uterine wall (placental abruption). It is important to note, however, that most women with the factor V Leiden mutation have normal pregnancies.

For more information and support, go to www.fvleiden.org 

http://www.netdoctor.co.uk/diseases/facts/factorv.htm