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 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.
