How Does Your Thyroid Affect Fertility?

Your thyroid gland is a small butterfly-shaped organ that makes your body’s supply of thyroid hormones.  Located at the front of your neck, just above your collar bone, your thyroid gland controls your metabolism.

Your thyroid gland secretes the thyroid hormones, thyroxine (T4) and triiodothyronine (T3).

Your thyroid hormones have many jobs, including:

  • regulate appetite and absorption of glucose in the intestines (study)

  • impacts body weight and insulin sensitivity(study)

  • regulate heart rate and body temperature (study)

  • regulate oxygen consumption and mitochondrial activity(study)

  • are important in growth and development including brain development (study)

And… your thyroid hormone levels also play a big role in your ability to get pregnant and stay pregnant.


Hypothyroidism is a condition where your body either produces too little thyroid hormone or has problems converting the less active thyroid hormone (T4) to the more potent form (T3). Doctors categorize it as clinical or sub-clinical hypothyroidism, depending on the degree of impairment.

The American Association of Clinical Endocrinologists and the American Thyroid Association sets the guidelines and the clinical definitions of hypothyroidism in the U.S.

Their list of clinical symptoms includes:

  • Cognitive impairment (e. brain fog)

  • Diastolic hypertension (high bottom number in blood pressure)

  • Course facies (coarse facial features, or a puffy face)

  • Goiter (enlarged thyroid gland)

  • Hypothermia (lower body temperature)

  • Lateral eyebrow thinning (ends of the eyebrows are thin or non-existent)

  • Macroglossia – (enlarged tongue)

  • Periorbital edema (puffiness under the eyes)

  • Delayed relations phase of deep tendon reflexes (ankle reflex test)

  • Lab results that include elevated CRP, LDLc, triglycerides, and others

  • Heart electrocardiograph changes

Hypothyroidism and Trying To Conceive:

Research shows that women who are hypothyroid are at a higher risk for infertility. One study on infertility found that 24% of the women were hypothyroid, compared to a normal population rate of 2 – 4% hypothyroidism.(study) Other studies show similar results with 14-24% of infertile women having hypothyroidism.(study) (study)

The good news is that correcting the thyroid levels helps with conceiving!

A study of hypothyroid women who had previously been unable to conceive found that thyroid hormone medication restored fertility in over 76% of the women.(study)

Women with subclinical hypothyroidism also benefit from thyroid hormone treatment when trying to conceive. A study found that women treated with T4 thyroid medication for subclinical hypothyroidism had higher pregnancy rates and conceived more quickly. (study)

Thyroid hormone levels are also important for egg quality and in vitro fertilization. In a study of women with subclinical hypothyroidism who were undergoing IVF, the women who receive thyroid hormone treatment (T4 only) had higher quality embryos, lower miscarriage rate, and higher live birth rate than those who did not receive T4 treatment. (study)

Animal studies also show that long-term hypothyroidism reduces ovarian reserve. This may be one cause of premature ovarian insufficiency. (study)

PCOS and Hypothyroidism:

Polycystic ovarian syndrome (PCOS) and hypothyroidism often go hand-in-hand.

Women with PCOS often do not ovulate every month, thus leading to problems when trying to conceive. Hypothyroidism is also associated with infrequent menstruation and lack of ovulation. (study)

A recent meta-analysis combined the data from several studies on PCOS and hypothyroidism. It found that women with PCOS were at double the risk for subclinical hypothyroidism.  (study)

Male Fertility and Hypothyroidism:

Thyroid hormone levels are also important for men, of course!  Men with hypothyroidism have decreased sperm production and decreased sperm motility. This leads to problems with fertility. (study)(study)

Testing for Thyroid Problems:

The only way to truly know your thyroid status is to get a blood test done.  Most doctors include a TSH test in your annual blood work.

TSH (thyroid stimulating hormone) is produced by the pituitary gland. It acts as a signal to the thyroid gland, telling it to increase production of the thyroid hormones. Normal TSH levels range from 0.4 to 4.9 mU/L. Some practitioners use 4.0 as the top end of the normal range.

While TSH is the most common test performed, it often doesn’t reflect your actual thyroid status.  It just shows how much of the signal is being sent to the thyroid -- not how much hormone the thyroid is producing.

Three other tests that are important for thyroid status are:

  • fT4: free T4 measures the amount of T4 available to enter the bloodstream.

  • fT3: free T3 measures the amount of unbound T3 available. T3 is the more potent thyroid hormone.

  • rT3: reverse T3 inactivates T3 to control the levels of fT3.

Other important tests both for thyroid function and in trying to conceive are thyroglobulin (TG) antibodies and thyroid peroxidase (TPO) antibodies test. Autoimmune thyroid diseases (Hashimoto’s and Grave’s) cause elevated TPO antibodies.

One significant cause of multiple miscarriages is also elevated TPO antibodies. Read more about that here.

If you don't have health insurance or your doctor won't order these tests, you can order them yourself online by clicking on the links below:

Genes Play a Role in Thyroid Function:

Both your environment and your genes influence your thyroid hormone levels.

Your TSH level, controlled by the pituitary gland, sends the signal to your thyroid gland to produce thyroid hormone. When your body’s levels of T3 and T4 are high, the pituitary sends less of the signal so your TSH levels drop. When your level of T3 and T4 are low, TSH levels will rise, telling the thyroid to produce more hormone.

Researchers think that your genetic variants control ~40% of your TSH level. (study)

One gene that modifies your TSH levels is the PDE8B gene. If you have your genetic data from 23andMe, AncestryDNA, etc., you can check to see how your PDE8B genetic variants are affecting your TSH levels.

Check your genetic data for rs4704397:

  • AA: increase in serum TSH (study)(study)

  • AG: increase in serum TSH

  • GG: no increase in serum TSH

Check your genetic data for rs6885099:

  • AA: increased serum TSH (study)

  • AG: increased serum TSH

  • GG: normal serum TSH

Your thyroid mainly produces T4, which is the inactive form of the hormone. Tissues throughout your body can then convert the T4 to T3, the active form.  This conversion from T4 to T3 uses the deiodinase enzyme, coded for by the DIO1 and DIO2 genes. These reactions need both iodine and selenium. (study)

Check your genetic data for rs2235544:

  • AA:  less conversion to free T3(study)(study)(study)

  • AC: somewhat increased fT3

  • CC: increased fT3 (study)

Check your 23andMe results for rs11206244 (v.4, v.5):

  • TT: higher rT3, lower free T3, higher fT4  (study)(study)

  • CT: lower free T3

  • CC: normal

Check your 23andMe results for rs225014 (v.4):

  • CC: decreased T4 to T3 conversion(study)

  • CT: decreased T4 to T3 conversion

  • TT: normal DIO2 enzyme, less likely to get Hashimoto's(study)

What can you do to support thyroid health?

The foods you eat support your thyroid function through essential nutrients and minerals.  It is important to get enough vitamin C, zinc, selenium, iron, iodine, and magnesium.

Eating a healthy diet of whole, unprocessed foods are essential to both overall health and thyroid health.

Getting enough overall calories is important for thyroid health. If you have been on a low calorie or low fat diet for a while and have noticed an increase in hypothyroid symptoms, you may want to investigate whether you need to add more nutrient-dense foods into your diet. (study)


Zinc is vital to good thyroid health, and studies show that it is often low in women with hypothyroidism.  Several studies have shown that supplementing zinc increased serum free T3 levels in women with subclinical hypothyroidism. (study) (study) (study)


Case reports and studies from a fertility clinic show that most women with hypothyroidism are also low in magnesium.  The study also found that pregnancies increased as magnesium levels increase. (study)(study) (study)


Vital for thyroid hormone synthesis, your body requires small amounts of iodine. The European Food Safety Authority sets the recommended daily amount at 150mcg/day. When iodine levels are low (less than 50 mcg/day), a goiter may develop. (study)

Seaweed is a very rich source of iodine. Wakame, which is used in miso soup, and nori, used in sushi, are the most commonly eaten seaweeds. Seafood and fish are also good sources of iodine. In many countries, table salt has iodine added to it to prevent goiters.


Selenium is another trace mineral that is integral to thyroid hormone production. Selenium is so important that your body prioritizes its use to the thyroid; deficiencies in selenium usually affect thyroid function last.

In autoimmune thyroid disease, clinical trials have shown that selenium helps to reduce TPO antibody levels. In fact, a study showed that for a third of the patients, selenium alone was able to reverse subclinical hypothyroidism.(study)(study)(study)

Nigella sativa:

Black cumin seed, also called Nigella sativa, has been shown in animal studies to both increase serum T4 and increase the number of offspring. (study)

Studies of women with Hashimoto’s found that powdered black cumin seed reduced BMI and cholesterol when compared with a placebo.  (study)


In addition to producing TSH, your pituitary gland also produces melatonin at night. TSH levels actually regulate some of the key enzymes needed to make melatonin. And melatonin, in turn, increases some of the key players in thyroid hormone production.

In addition to being important for thyroid function, melatonin is also essential for egg quality and fertility.

Prioritizing good sleep and blocking out blue light from your TV, laptop, and phone at night can help raise melatonin levels.

For more about melatonin, read this article.

Eliminating toxins that harm your thyroid:

Eliminating thyroid-harming toxins is just as important as thyroid supporting nutrients.

Studies show that exposure to commonly used pesticides decreases free T4.  This is a large problem for both farm workers and for people living in agricultural areas where pesticides may leech into the water supply. (study)(study)

Regardless of where you live, one way to decrease your exposure to pesticides is to choose organic foods whenever possible. This is important both when trying to conceive as well as during pregnancy. Studies show that organochloride pesticide exposure during pregnancy alters both the mother’s thyroid hormones and can affect the fetus. (study)

Bromide is also harmful to your thyroid gland.  Structurally, bromide is like iodine and can be absorbed into the thyroid in place of iodine. This can eventually lead to a decrease in thyroid function.(study)(study)(study)

Sources of bromide in your environment include fabrics and furniture sprayed with flame retardant and hot tubs containing brominated chemicals.

Important Takeaways: 

  • Thyroid health is essential for a healthy pregnancy.

  • If you have symptoms of hypothyroidism, go beyond just testing TSH. Include free T4, free T3, reverse T3, and TPO antibody blood tests to truly know your thyroid status.

  • Healthy foods and a healthy environment are vital to thyroid function. Getting enough magnesium, selenium, iodine, and zinc are important.

  • Avoid toxins that zap your thyroid.

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What to Do After a Miscarriage

Almost 15% of pregnancies will end in miscarriage, most often during the first few weeks of pregnancy. Even knowing the statistics, miscarriages are heartbreaking.

The sorrow often comes with questions – why did it happen and what can be done to prevent it from happening again?

Tests Performed After a Miscarriage

After a miscarriage, your doctor may want to investigate why it happened through several clinical test procedures. Testing for the root cause is even more important after multiple miscarriages.

Tests that your doctor orders may include:

  • Hysterosalpingogram: an x-ray with contrast to check the structure of the uterus.

  • Hysteroscopy: an examination of the uterus with a fiberoptic telescope.

  • Saline sonohysterogram: an ultrasound of the uterus filled with saline.

  • Vaginal ultrasound: examines the uterus, ovaries, and fallopian tubes.

  • Endometrial biopsy: looking for infection in the endometrial tissue

  • Uterine lining testing: an endometrial biopsy on cycle day 21 to test for thickness of the uterine lining.

  • Hormone tests: usually checking prolactin, progesterone, and thyroid levels

  • Antibodies testing: looking for lupus antibodies or antiphospholipid antibodies.

  • Genetic testing of either the parents or the fetus: 50-70% of early miscarriages are due to genetic abnormalities of the embryo. (study)

Not all of these tests are necessary for every woman after a miscarriage.

But what do you do if all the tests come back negative? If your uterus is structurally perfect and your hormone levels are within range – what next?

This is a frustrating situation that many women face, especially after age 35!

Digging deeper into miscarriage risk

As women age, it becomes more and more important to optimize for a healthy pregnancy.

But what is “healthy” and how do you know if your health is optimal when trying to conceive?

Several common blood tests can help you to quantify – to actually KNOW – what your levels are for several important biomarkers.

Your doctor can order these tests.  Many of the tests mentioned below are covered by insurance but check first so you don't get an unexpected bill.

If you have a high deductible, it may make more sense to pay out-of-pocket for blood work and submit your receipt to the insurance company to see if your expenditure can count towards your deductible.

If you don't have insurance or you have a high deductible, you can order and pay for your own blood tests to quickly get the information you want.

In most US states (except NY, NJ, RI), you can order your own blood tests online. Note that health insurance will not cover the lab tests that you order online, but you may be able to use your HSA or FSA account to pay for the tests.

The links provided below for online tests are with the company I work with who I found to have the best prices.  They offer tests at a fraction of the cost that insurance would charge.

The testing process is simple.  Using my affiliate links (full disclosure: I get a commission) provided below, you add the test to your shopping cart.  After you pay for the test, you will get an order form to print out and take to a local blood draw location at Quest Diagnostics. Then you go to get the blood draw done whenever it is convenient for you. The test results are sent to the company, which notifies you via email when your results are available to print out. It normally takes a couple of days to get the test results.

You can take the results to your doctor for advice or share them with your fertility coach.

Testing for Autoimmune Thyroid Diseases:

A TPO (thyroid peroxidase) antibody test looks for indications of autoimmune thyroid diseases such as Hashimoto’s or Grave’s disease.

Several studies have shown that women with TPO antibodies are at a higher risk of miscarriage – with one study showing a 2-fold increase in risk! (study)(study)(study)

You can order a TPO antibody test here.

A full thyroid test panel is recommended to get a more complete picture of your thyroid function.  That can ordered here.

What can you do about TPO antibodies?

While TPO antibodies can be present without thyroid disease, a positive TPO antibodies test is something that you should discuss with your doctor. Further testing may be needed to determine if you should be prescribed thyroid medication.

Adopting a healthy diet is helpful in managing autoimmune thyroid conditions.

Look into environmental or dietary triggers for TPO antibodies such as mold, iodine excess, and heavy metals. Make sure you are getting an adequate amount of selenium in your diet. (study)

Homocysteine Levels:

Homocysteine is an important marker for increased risk of heart disease. High homocysteine levels are also associated with increased risk of fertility problems.  Women with high homocysteine are at an increased risk for placental abruption, recurrent miscarriages, and high blood pressure during pregnancy. (study)(study)(study)(study)

A simple blood test can tell you if you have a high homocysteine level. Order here.

 Solutions for high homocysteine levels:

Diet plays a big role in homocysteine levels. Make sure you are getting plenty of folate, vitamin B6, and vitamin B12.

If you aren’t getting enough of these vital micronutrients via your diet, consider taking a good prenatal vitamin that contains the active forms of these B-vitamins: methylfolate, methylcobalamin, and P5P.    For more information about folate and vitamin B12, click here.

Vitamin D testing:

Many studies have shown that women with low vitamin D levels are at a higher risk for miscarriages. Women undergoing IVF are more likely to get pregnant if their vitamin D levels are “sufficient”. (study)(study)(study)

How much vitamin D do you need? Vitamin D deficiency is defined as having a 25(OH)D level less than 20 ng/ML, and vitamin D insufficiency is defined as having levels between 20-32 ng/ml.  Normal levels in sunny countries are between 54-90ng/ml. (study)

Instead of guessing, a simple 25(OH)D test can tell you what your vitamin D level is. The test can be ordered here.

Solutions for low vitamin D:

 Your body makes vitamin D through exposure to sunshine on your bare skin. The best time of the day to get plenty of sunshine is between 10 am and 2 pm.  If your test results show that your vitamin D levels are less than optimal and you can’t get enough sunshine, you can  also supplement with vitamin D. Look for a brand that includes the vitamin D with a good source of fat.

Read more: How Vitamin D Improves Fertility and Egg Quality

Testing for Inflammation:

C-reactive protein (CRP) is a biomarker that shows your overall inflammation level.  CRP is an inflammatory marker that is released by the liver. If it is elevated, it indicates inflammation, but it doesn’t tell you what is causing the inflammation.

Several studies have shown that women with higher CRP levels are at an increased risk of having multiple miscarriages. (study)(study)(study)

When ordering a CRP test, the high sensitivity CRP test is your better option.  Order here.

Solutions for high CRP:

 Talk with your doctor about low dose aspirin therapy if you have high CRP levels. A recent study showed that for women with high CRP daily aspirin brought their miscarriage risk back down to normal. (study)

Testing for Iron Deficiency:

A simple blood test for anemia can tell you if you have low iron levels that could be affecting your ability to conceive.  Order online here.

Women with severe anemia are at a much higher risk of miscarriages.(study)(study)

Solutions for iron deficient anemia:

Iron-deficient anemia can be reversed by eating foods high in iron, such as liver. Iron supplements are also available, but if you are taking a prenatal vitamin, check the label first to see if it already has iron in it.  Lactoferrin is a good alternative to iron supplements, especially for women with clotting disorders. (study)

Testing for Clotting Disorders:

Blood clots can be a cause of recurrent miscarriages. More about that here.

If you have a family history of clotting disorders, such as a first degree relative who has had a deep vein thrombosis or pulmonary embolism, you should talk with your doctor about testing for clotting disorders.

A PTT (partial thromboplastin time) test and PT/INR test can tell you if your blood clots slowly or quickly. Many doctors and fertility specialists can do this test in the office for you.  You can also order here.

A low PT result shows that your blood clots more quickly than normal. Your doctor or fertility specialist may want to investigate further to see if you carry genetic variants that cause clotting disorders such as factor V Leiden.

An antiphospholipid antibodies (anticardiolipin antibodies) test can tell you if you have an autoimmune condition that causes your blood to clot more rapidly. Your doctor can order this test for you, or you could order it through an online lab company ($147 from Walk In Lab).

Solutions for clotting disorders:

Your doctor should determine if the clotting disorder is serious enough to warrant anticoagulant medications.

If you aren’t in need of prescription medications, add natural blood thinners to your diet.  Fish oil is a natural blood thinner. Adding more fish to your diet is great when trying to conceive. Just make sure to choose fish that are low in mercury.  Or a high quality fish oil supplement is an easy addition to your daily routine.

Natural compounds in cacao have a blood thinning effect like low-dose aspirin! (study)(study)  Try snacking on a handful of organic cacao nibs for an afternoon pick-me-up.

Moving forward:

Taking steps to optimize your health can be powerful in recovery from a miscarriage!

Testing can help you map out a plan to move forward when you are ready to try again to conceive.

Read More

How DHEA Improves Egg Quality

If you’ve done IVF, your doctor might have recommended DHEA supplementation before your IVF cycle started.  Or you might have come across DHEA as a way to improve egg quality in your research.

So does DHEA improve fertility?  Research indicates promising results with the use of DHEA supplementation.  Some doctors offer it for women with diminished ovarian reserve (DOR) as indicated by low AMH and/or high FSH, premature ovarian aging (POA), poor responders to previous IVF cycles, and for women over 40 whose ovarian reserve is declining due to aging.

What is DHEA?

Read More

How does CoQ10 Improve Egg Health in the Older Woman?

Choosing the right supplements when trying to get pregnant is confusing with all the choices available.  However, some become increasingly important as you get older.  One of them is CoQ10.

How does CoQ10 improve egg quality to help a woman in her late 30s or 40s get pregnant?  CoQ10 helps the eggs produce the vast amount of energy needed for all stages of conception – from ovulation, fertilization, implantation, to division from one cell into a healthy baby.  CoQ10 is also a powerful antioxidant which protects the eggs from damage caused by aging, inflammation, and environmental sources.

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How healthy are you? Take this simple test...Part 4

This is the 4th installment of a series.  Read part 1part 2, and part 3 first before you go any further.

So now you might suspect that part of the reason why you may not be getting pregnant is that you have too much estrogen relative to your other hormones.

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How healthy are you? Take this simple test...Part 3

Did you miss part 1 and part 2 of this series?  Read those first.  Then come back here.  

If your calculated waist-to-hip ratio (WHR) is greater than 0.85 for women or 0.90 for men, that might be an indication of too much estrogen circulating in your body.

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How healthy are you? Take this simple test...Part 2

Today's a continuation of yesterday's email so if you missed it, STOP!  Read this first

If you have your waist-to-hip ratio (WHR), let's talk about what it means to you and potentially your fertility and long-term health...

According to the World Health Organization, a healthy WHR is:

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How healthy are you? Take this simple test...Part 1

You know what's dumb?  Posting a picture of yourself with a better looking dude in an online dating app.  So disappointing!

People often choose based on looks.  Don't tempt me with the buffet in your profile pics but tell me my option is the wilted salad.  That's just messed up.

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