What you should know

Do you have trouble getting pregnant? Your or your husband’s thyroid could be the problem, because thyroid disorders can cause fertility difficulties for men and women. While infertility can be triggered by various factors, suboptimal function of the thyroid gland may be that “missing link”, especially when thyroid disease runs in your family. Once the thyroid disorder is treated, you should no longer face fertility problems providing that the thyroid was the only reason for infertility. This website aims to raise your awareness of the link between the thyroid and infertility

If you have been unsuccessfully trying to fall pregnant for longer than the necessary six months to a year, see your doctor to check your thyroid hormone status, before starting other medical procedures. If the thyroid is the cause of your infertility, getting it under control restores fertility and reduces your risk of health complications.

Know the facts

Thyroid hormones interact with other, mainly sexual hormones.1 The right amount of thyroid hormones is necessary to preserve a normal function of the testes in men and the ovaries in women. Too much (overactive thyroid) or too little (underactive thyroid) of these hormones can adversely affect male and female fertility.
The optimal function of the thyroid gland is not only beneficial to the health of parents, it is crucial for the health of the baby. Suboptimal thyroid levels are a cause of fertility problems, increased risk of miscarriage, premature delivery and other complications, and they may impair brain development in a fetus, too.2
Male infertility is involved in 30 percent of couples’ inability to achieve pregnancy, 35 percent is related to female causes, 20 percent to both parties’, and in 15 percent no cause can be identified and the spermogram and female work-up are both normal.3

How thyroid hormones impact male infertility

There are many reasons for male infertility such as hormonal imbalances, physical, psychological or behavioral problems. Thyroid hormones, previously thought not to affect male fertility, are now being recognized as having an important role e.g. in sperm production.4,5 The good news: Correction of these disorders may restore a man’s fertility.

The overactive thyroid

If your thyroid gland produces and releases excess thyroid hormones into the bloodstream you have hyperthyroidism. Men can develop hyper¬thyroidism for a number of reasons, including Graves’ disease, overmedication with thyroid hormones for treatment of hypothyroidism, too much iodine in the diet, thyroid nodules, or an inflamed thyroid gland (known as thyroiditis). By speeding up your body’s metabolism, hyperthyroidism may result in many different symptoms; some of them are often mistaken for simple nervousness or stress.6

Key symptoms of hyperthyroidism

  • Nervousness
  • Irritability
  • Fast heart rate
  • Weight loss
  • Increased sensitivity to heat
  • Muscle weekness
  • Increased sweating
  • Trembling hands
  • Hair loss
  • Erectile dysfunction
  • Infertility

If you are having fertility problems and at the same time some of the symptoms6 – it is unlikely you would develop all of them – you should bring up thyroid disease with your doctor, especially if you have a family history of thyroid disease.

The underactive thyroid

If your thyroid gland produces not enough thyroid hormones, you have thyroid deficiency, medically known as hypothyroidism. The most common causes of hypothyroidism are iodine deficiency and, where iodine deficiency is uncommon, Hashimoto’s disease, an autoimmune disease that progressively destroys your thyroid gland.7 Thyroid deficiency slows down your metabolism Poor thyroid function5 is often associated with reduced libido and erectile dysfunction; furthermore it has an adverse effect on the form and structure of sperm – all of which can give rise to infertility.

Key symptoms of hypothyroidism

  • Fatigue
  • Mental fogginess
  • Poor concentration and memory
  • Depression
  • Increased sensitivity to cold
  • Weight gain
  • Constipation
  • Dry skin and hair
  • Brittle nails
  • Joint or muscle pain
  • Loss of libido
  • Erectily dysfunction
  • Infertility

If you are having fertility problems and at the same time some of the symptoms you should see your doctor and tell him/her about your symptoms.

How thyroid problems impact female infertility

Thyroid hormones interact with your reproductive hormones, estrogens and progesterone, to preserve normal function of the ovaries and maturation of the egg (oocyte).1 If your thyroid gland releases of too much (hyperthyroidism) or too little (hypothyroidism) thyroid hormones, the balance of reproductive hormones can be impaired5 with consecutive thyroid-related fertility problems such as ovulation disorders, irregular periods, and trouble getting pregnant or carrying a baby to term.8 Even though you may be having a regular menstrual period, you may not be ovulating. Since thyroid disease is a common endocrine disorder in women of childbearing age, the first thing to do when you have troubles getting pregnant is to have your thyroid checked, especially if thyroid disease runs in your family.

The overactive thyroid

Hyperthyroidism is ten times more common in women than inmen9 and can cause a woman to have difficulties in not only getting pregnant, but also staying pregnant. If your thyroid gland releases excessive amounts of thyroid hormones into the bloodstream, you are hyperthyroid. The most common reason for hyperthyroidism in young women is Graves’ disease, an autoimmune disorder where antibodies mistakenly attack the thyroid gland. This stimulates the gland to overproduce thyroid hormones.6 If you experience unhealthy weight loss, this can hamper your chances of falling pregnant, too.10

The underactive thyroid

When you have a family history of thyroid disease or any autoimmune disease you have an increased risk for hypothyroidism.11 If your thyroid gland produces too little thyroid hormones, TSH will increase to stimulate your thyroid gland to fill up the gap. Elevated TSH has been observed in 4.6% of cases of female infertility.12

Key symptoms of hypothyroidism

  • Fatigue
  • Mental fogginess
  • Poor concentration an memory
  • Weight gain
  • Increased sensitivity to cold
  • Muscle or joint pain
  • Dry skin and hair
  • Brittle nails
  • Abnormal periods
  • Loss of libido
  • Erectily dysfunction
  • Infertility

If you were hypothyroid you could have infrequent and light menstrual bleeding, no menstrual cycles or irregular cycles due to problems with ovulation. These menstrual irregularities are approximately three times more common in hypothyroid women than in women with normal thyroid function.5 With a low-functioning thyroid, levels of prolactin, the hormone that stimulates breast milk production after delivery, may increase and inhibit ovulation.5 Hypothyroidism is also associated with an increased risk of polycystic ovarian disease (PCOS), a condition that causes cysts on the ovaries and inhibits pregnancy.13

How thyroid diseases are treated


Once your overactive thyroid is diagnosed by blood tests, therapy will reflect the type of your hyperthyroidism, your age and health status, and how serious the overactivity is. The treatment options are:

Anti-thyroid drugs, which prevent the thyroid gland to produce new thyroid hormones without destroying the thyroid gland6

Radioactive iodine radiation, which destroys thyroid tissue and stops thyroid hormone production6

Surgical removal of parts or of the whole thyroid gland6
The last two options will lead to hypothyroidism, which is managed by adding levothyroxine

In women, having radioactive iodine treatment before becoming pregnant usually eliminates the need for antithyroid drugs. For prophylactic reasons a woman should wait at least six months after radioactive iodine treatment before trying to become pregnant.5 Men who have had radioiodine treatment should wait four months before fathering a child.5


Once your underactive thyroid is diagnosed by blood tests your physician will prescribe the missing thyroid hormones by T4 replacement. You will be given levothyroxine, a synthetic thyroxine that works exactly like the thyroid hormone produced by your thyroid gland7, which usually improves or normalizes menstrual irregularities in women and sperm abnormalities and erectile dysfunction in men, thus restoring fertility.5 If your hypothyroidism results from too little iodine in your diet, you will be given iodine supplements.

Mild hypothyroidism

When your thyroid hormone levels are only slightly abnormal (subclinical), your doctor may simply monitor your thyroid function, because there is no consensus on the benefits of treating patients with subclinical thyroid disease. Ask your doctor if he or she will treat your thyroid problem more aggressively to restore your fertility. When it comes to pregnancy, even mild untreated hypothyroidism in the mother is treated with thyroid hormone replacement therapy to prevent an adverse effect on brain development of the baby.14


  • 1– Poppe, K, Glinoer D, Tournaye H et al. Thyroid function and assisted reproduction. In: The Thyroid and Reproduction, METS Riga 2008. Georg Thieme Verlag
  • Stuttgart 2009; 33-38.
  • 2– American Thyroid Association. General Information (2012) Accessed October 2012.
  • 3– Healy DL, Trounson AO, Andersen AN. Female infertility: causes and treatment. Lancet 1994; 343:1539–1544.
  • 4– Meikle AW. The interrelationship between thyroid dysfunction and hypogonadism in men and boys. Thyroid 2004; 14 (Suppl 1): S17-S25.
  • 5– Krassas GE, Poppe K, Glinoer D (2010) Thyroid function and human reproductive health. Endocr.Rev. 2010 31:702-755.
  • 6– The American Thyroid Association (2012) Hyperthyroidism October 2012.
  • 7– The American Thyroid Association (2012) Hypothyroidism Brochure. Accessed October 2012.
  • 8– Bercovici JP. Menstrual irregularities and thyroid diseases. Feuillets de biologie 2000; 74: 1063-1070.
  • 9– Vanderpump MPJ, Tunbridge WMG, French JM et al. The incidence of thyroid disorders in the community: A twenty-year follow-up of the Whickham Survey. Clin
  • Endocrinol 1995; 43: 55-69.
  • 10– Green BB, Weiss NS, Daling JR. Risk of ovulatory infertility in relation to body weight. Fertility and Sterility 1988; 50 (5): 721-726.
  • 11– The Hormone Foundation’s Patient Guide to the Management of Maternal Hypothyroidism Before, During, and After Pregnancy. De Groot LJ, Stagnaro-Green A,
  • Vigersky R, The Hormone Foundation 2007
  • Accessed October 2012.
  • 12– Grassi G, Balsamo A, Ansaldi C et al. Thyroid autoimmunity and infertility. Gynecol Endocrinol 2001; 15: 389–396.
  • 13– Beyond Infertility. Polycystic Ovary Syndrome (PCOS). U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES. National Institutes of Health; Eunice Kennedy
  • Shriver National Institute of Child Health and Human Development 2008
  • Accessed October 2012.
  • 14– De Groot L, Abalovich M, Alexander EK, Amino N, Barbour L et al. Management of Thyroid Dysfunction during Pregnancy and Postpartum: An Endocrine Society
  • Clinical Practice Guideline. J Clin Endocrinol Metab 2012; 97 (8): 2543-2565.
  • If you want to know more about thyroid and fertility, visit the following websites:
    Patient information provided for International Thyroid Awareness Week
    Patient information by the Endocrine Society
    Patient information by Merck Serono
    Patient information by the Thyroid Federation International
    Patient information on thyroid health published by the American Thyroid Association (ATA)
  • The information in this website is not intended as a substitute for informed medical advice. You must consult a suitably qualified healthcare professional on any problem or matter which is covered by any information in this website before taking any action.
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