Why Do I Keep Having Miscarriages?

Estimated reading time: 9 minutes

How Many Women Have Miscarriages?

It is estimated that 1 in 4 known pregnancies end in miscarriage, and up to half of all pregnancies since many women miscarry before they realize they’re pregnant. For women who have had two or more consecutive miscarriages, up to 70% will go on to have a healthy baby. It’s likely that most miscarriages in the first trimester happen because of a chromosomal abnormality of the fetus. Half of the cases of recurrent miscarriages have no explanation.

For most women, you have an 80% chance of a subsequent successful pregnancy. The likelihood of another miscarriage is about 1 in 6 for women under 35. 1 out of 100 women trying to conceive will have three or more consecutive miscarriages. Suppose you have had two or more miscarriages. In that case, you should probably see a fertility specialist in reproductive endocrinology and infertility who can help you sort out why you have recurrent miscarriages and plan what to do about it.

What Causes Miscarriage?

Searching for miscarriage causes? Here are

Biological factors include females over 35 or a male partner over 40, genetic defects of the embryo, or uterine abnormalities.

Lifestyle factors may include over or under a healthy weight, smoking ½ a pack a day or more, alcohol consumption, cocaine use, and regularly lifting over 220 pounds.

Health factors like uncontrolled diabetes, hypertension, thyroid disease, lupus or other autoimmune disorders, blood clotting issues, and sexually-transmitted infections raise your risk.

Environmental factors may include heavy-metal exposures, certain medications, stress, etc.

Clotting disorders may include Antiphospholipid antibodies, Factor V Leiden, and Lupus anticoagulants which are conditions that increase the risk of miscarriage. Additionally, low progesterone or high prolactin levels can increase your risk of a miscarriage, more on progesterone below.

Common Myths About Miscarriage

This list of activities has no connection to miscarriage, despite it being popular belief.

• Routine physical activity
• Full-time employment
• Standing for more than 6 hours per day
• Screen time
• Air travel
• Sex
• Caffeine
• Tampons
• Birth control pills
• Flu shots and COVID shots.

How to Reduce Miscarriage Risk

Reducing your risk of another miscarriage includes healing physically and emotionally, talking to your doctor about the timing of your subsequent pregnancy, giving up bad habits, controlling your chronic medical problems, keeping a healthy weight, and reducing caffeine to 1 cup per day, and treating deficiencies you might have.

What is the MTHF-Reductase Mutation? And How does it Relate to Homocysteine?

There’s been a lot of interest in MTHF-Reductase gene mutations recently. This stands for methylenetetrahydrofolate reductase, an enzyme necessary for metabolizing folate. Folate is needed to build DNA and to reduce homocysteine levels in your blood. A mutation in the MTHF-Reductase gene can reduce the enzyme’s activity, leading to elevated homocysteine levels.

Elevated homocysteine can cause blood clotting and platelet aggregation. Platelets are the tiny blood cells that clump together to form clots in your body. This happens all the time but usually is tightly controlled. Homocysteine damages the inner layer of blood vessels, which causes platelet clumping and blood clotting. Clotting in the placenta can lead to pregnancy harm or loss.

Two MTHF-Reductase mutations are most common, the C677T and A1298C variants. Health problems are associated with the 677 variant. This occurs in nearly half of Americans. About 1 in 4 Hispanics and up to 1 in 6 Caucasians are homozygous for this, meaning they have the gene defect from both parents. To be heterozygous means you only have 1 of the genes. Having both gene defects is worse than only having one. The 1298 variant rarely causes problems and is found in 7 to 14% of North Americans, Europeans, and Australians and is much less common in Hispanic and Asian populations.

What Does the MTHF-Reductase Mutation Do?

MTHF-Reductase mutations are also associated with preeclampsia, anemia, neural tube defects, and miscarriage. Some suggest that it is associated with depression, schizophrenia, and bipolar disorder, however, none of these have been proven to be caused by a gene mutation.

What Else Raises Homocysteine Levels?

Other causes of elevated homocysteine levels include low thyroid activity, diabetes, high cholesterol, hypertension, obesity, couch potato lifestyles, and medications like atorvastatin and methotrexate. Not to mention a few others.

Is There a Test for the MTHFR Mutation?

The American College of Obstetrics and Gynecology, or ACOG, does not suggest testing for the MTHF-Reductase gene unless you also have elevated homocysteine levels. But if you want you can do a home test with commercial gene companies such as 23andMe.com, which costs about $200; For about $80 you can get another test called At Home MTHFR by Empower Dx.

How Do You Treat the MTHFR Mutation?

Treatment of the MTHFR gene mutation during pregnancy may include a methionine-restricted diet, 100 mg of aspirin daily, vitamins B1, B2, B3, B6, B9, and B12 daily, and folic acid 5 mg twice weekly, and Lovenox, a blood thinner. But even gene defects do not occur in a vacuum all by themselves. Other factors we noted above could also affect pregnancy health.

What is Folate (Folic Acid) and What Does it Do For Pregnancy?

Pregnancy increases the need for folate, and we routinely supplement with folic acid several months before you wish to become pregnant to reduce neural tube defects such as spina bifida or anencephaly. That alone makes folate important.

More Sources of Folic Acid

How Does the Body Use Folate?

Your body metabolizes dietary folate into the active form THF, tetrahydrofolate. Our bodies cannot make folic acid, a supplement also commonly called vitamin B 9. Folic acid is converted to the active form in the gut to 5-MTHF, and the liver also does it, but this can take some time. Even small doses may not be entirely metabolized by the body when you take your next dose. But the conversion can be enhanced by taking other B vitamins. By the way, folate or B9 is a water-soluble vitamin. This means any you don’t use gets dumped out in the urine. You can’t store it in your body, so you take it daily. BTW, “vitamins” comes from the notion that they are “vital amines” to the body that we can’t make so we take supplements.

People with MTHFR mutations, or high homocysteine levels due to folate or vitamin B12 deficiencies can take either Folic acid and/or B12. Some people think that the methylated form of folate is better for the body, but even if you have the gene mutation, you can still take Folic acid. There is evidence that the body better utilizes the L-methyl folate form. The methylated form is called 5 – MTHF, which is also available as levomefolate calcium or levomefolate magnesium, which is sold online as Metafolin, Deplin, Enlyte, and others.

Does Low Progesterone Cause Miscarriages?

Low progesterone levels are associated with miscarriage, but it’s not clear if it’s the actual cause. Supplementing with progesterone seems to reduce miscarriage in those who have had multiple miscarriages. The name comes from the fact that it has Pro-gestational activity. It is the primary hormone that supports pregnancy. When the ovary ovulates and releases an egg, the corpus luteum left behind makes progesterone. If there is no pregnancy, it fades away. If pregnancy occurs, progesterone production supports the pregnancy until about 7 to 9 weeks. At that time, the placenta takes over progesterone and estrogen production.

Do Progesterone Shots Prevent Miscarriages?

10 scientific studies involving nearly 1700 women found moderate evidence that taking progesterone was beneficial. However, there is no universal agreement on progesterone use for recurrent miscarriage. No studies have shown progesterone supplementation causes definite increases in congenital defects. A substitute called dydrogesterone also seems to have no adverse effects on babies, but there are many questions as to how to use it optimally.

Low progesterone is often blamed for recurrent miscarriage, but most often, low progesterone levels are a symptom of an unhealthy pregnancy. For example, there might be low levels of beta-hCG from the embryo. Beta-hCG triggers the production of progesterone and estrogen. Low levels of beta-hCG can lead to low levels of progesterone. But low beta-hCG may be due to chromosomal abnormalities of the embryo. In this case, supplementing with progesterone won’t fix the underlying chromosomal abnormalities.

It’s difficult figuring out what level of progesterone leads to a healthy pregnancy. To be clear, a single blood draw of progesterone levels will not give you the whole picture. Your fertility specialist can help you with this. For in vitro fertilization, or IVF, progesterone is necessary because the egg harvested in IVF does not have a normal corpus luteum that typically produces progesterone. Progesterone levels and beta-hCG levels can help predict healthy pregnancies.

What Do I Do Now?

Even one miscarriage can be devastating, and having more than one is very difficult. Many factors can contribute to that. Talking to your OB doctor is the best first step to a healthy pregnancy. If needed, you can see a fertility specialist to help you have a healthy pregnancy.

Remember, miscarriages are not your fault, you cannot control them, but you and your OB can try to improve your chances of a successful pregnancy.

To Your Good Health and Pregnancy,

Kevin McCurry, MD

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