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MTHFR and Recurrent Miscarriages - What's the Story?


Updated June 05, 2014

In looking for information about treatment of recurrent miscarriages, you will probably come across mentions of various unproven treatments. Researchers have many theories about causes of recurrent miscarriages but relatively few have treatments that are solidly grounded in conclusive evidence.

In the meantime, doctors often test for and treat potential causes of recurrent miscarriages that they feel have a solid theoretical base and for which they feel the potential treatment is unlikely to cause harm even if it does not help.

The practice of testing for MTHFR gene mutations falls into this category. Let's take a look at what MTHFR is and why some doctors feel it relates to miscarriages.

Current Status

Researchers have looked at MTHFR gene mutations as being a possible factor in recurrent miscarriages with quite mixed results. Some studies find that MTHFR gene variations increase the risk of miscarriages while others find no link.

Right now, some doctors test for MTHFR in patients with history of miscarriage and offer aggressive treatment to everyone with MTHFR gene mutations. Others do not ever test for MTHFR variants. There is currently no official recommendation and no conclusive evidence about the value of testing for MTHFR gene mutations, so practice varies widely.


MTHFR stands for methylenetetrahydrofolate reductase. This is an enzyme that is involved in amino acid metabolism in the body. Common mutations in the MTHFR gene can affect how a person's body processes homocysteine, an amino acid found in the blood.

People with MTHFR gene mutations may have elevated levels of homocysteine, although not everyone with an MTHFR gene mutation is affected. (Note that elevated homocysteine is considered a potential risk factor for miscarriages independently and can be caused by other factors beside MTHFR mutations.) People with MTHFR gene mutations can have a decreased ability to metabolize folic acid and other B vitamins, also.

Over the years, dozens of common and rare mutations in the MTHFR gene have been identified. Among the more common are mutations called C677T and A1298C, with the former often called the more problematic of the two. A person can be either heterozygous or homozygous for either or both of these MTHFR gene mutations (heterozygous would mean a person had one copy of the mutation and homozygous means that the person has two copies of the mutation).

MTHFR gene mutations are fairly common; nearly half the population of the United States may be at least heterozygous for an MTHFR gene mutation.

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