The Link Between Factor V Leiden and Recurrent Miscarriages

Why heparin and aspirin may help

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When your blood clots, many of the proteins in your body, among them Factor V, work together to make that happen; Factor V Leiden is a genetic variation of Factor V that affects the blood-clotting process and makes a person more likely to form blood clots.

Learn more about this genetic variation and what effect it may have on your pregnancy with this review.

Copies of the Factor V Leiden Gene

A person can have one copy of the Factor V Leiden gene and one normal copy (meaning the person is heterozygous), or a person can have two copies of the Factor V Leiden gene (the person is homozygous).

Some doctors recommend heparin for women with recurrent miscarriages who test positive for Factor V Leiden. Ask your doctor if she recommends heparin, another medication or no medication at all for you.

Protein C Resistance

The Factor V Leiden gene is also associated with a condition called activated protein C resistance. Protein C is another protein involved in the clotting process. The majority of people with activated protein C resistance also have the Factor V Leiden genetic variation. So, many women who haven't been specifically tested for the Factor V Leiden gene may discover that they're carriers after testing positive for protein C.

Statistics

About 4 percent to 7 percent of the population is heterozygous for Factor V Leiden. Around 0.06 percent to 0.25 percent of the population is homozygous for Factor V Leiden. Different ethnic groups have different rates of the Factor V Leiden mutation; it is most common in people from northern Europe.

Talk to your doctor about whether or not you're at risk.

Risks

Factor V Leiden means an increased risk of deep vein thrombosis and medically important blood clots. Some studies have found that having the Factor V Leiden mutation means an increased risk of recurrent miscarriages, possibly because of tiny blood clots blocking the flow of nutrients to the placenta.

Treatment

In pregnancy, some doctors believe in using heparin and/or low-dose aspirin to treat women who have the Factor V Leiden gene and a history of miscarriages. Currently, researchers are still studying this treatment to verify that it actually helps. Many fertility clinics recommend that patients take baby aspirin during treatment just in case they have clotting problems.

Relationship of Factor V Leiden to Miscarriages

Researchers are still studying the exact nature of the relationship between Factor V Leiden (and other hereditary thrombophilias) and recurrent miscarriages. Different genetic blood clotting disorders have different levels of relationship to miscarriage, but Factor V Leiden is one of the hereditary thrombophilias that does appear to have a role in causing miscarriages (or at least increasing risk), because women with the mutation have a higher rate of miscarriages than women without it.

Available research suggests that Factor V Leiden can play a role in miscarriages that happen after 10 weeks but it is less likely to be a factor in early miscarriages.

Many doctors do test for Factor V Leiden as a part of the recurrent miscarriage workup of tests and recommend treatment for those who test positive.

Sources:

Coulam, C.B., R.S. Jeyendran, L.A. Fishel, and R. Roussev, "Multiple thrombophilic gene mutations rather than specific gene mutations are risk factors for recurrent miscarriage." American Journal of Reproductive Immunology May 2006. Accessed 9 Mar 2008.

Foka, Z.J., A.F. Lambropoulos, H. Saravelos, G.B. Karas, A. Karavida, T. Agorastos, V. Zournatzi, P.E. Makris, J. Bontis, and A. Kotsis, "Factor V leiden and prothrombin G20210A mutations, but not methylenetetrahydrofolate reductase C677T, are associated with recurrent miscarriages." Feb 2000. Accessed 9 Mar 2008.

Jivraj, S., R. Rai, J. Underwood, and L. Regan, "Genetic thrombophilic mutations among couples with recurrent miscarriage." Human Reproduction May 2006. Accessed 9 Mar 2008.

Reznikoff-Etievan, M.F., V. Cayol, B. Carbonne, A. Robert, F. Coulet, and J. Milliez, "Factor V Leiden and G20210A prothrombin mutations are risk factors for very early recurrent miscarriage.' BJOG Dec 2001. Accessed 9 Mar 2008.

University of Illinois - Urbana/Champaign, "Patient Resources: Factor V Leiden." Hematology Resource Page. Accessed 9 Mar 2008.

Walker, M.C., S.E. Ferguson, and V.M. Allen, "Heparin for pregnant women with acquired or inherited thrombophilias." The Cochrane Library 21 Jan 2003. Accessed 9 Mar 2003.

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