Hypothyroidism and infertility: Any connection?

Hypothyroidism, like any other condition that disrupts hormonal function, can affect fertility in both women and men. However, in women, it can lead to ovulatory issues, such as irregular cycles, and increase the risk of miscarriage in patients with altered thyroid hormone levels.

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Does Hypothyroidism Affect Fertility?

Hypothyroidism is a condition that occurs when the thyroid gland—located at the base of the neck near the trachea—doesn’t produce enough thyroid hormones. These hormones, known as T4 and T3, are essential for regulating metabolism and many critical bodily functions.

The pituitary gland, located in the brain, controls thyroid function by releasing thyroid-stimulating hormone (TSH). When T4 and T3 levels drop, the pituitary produces more TSH to stimulate the thyroid. However, in hypothyroidism, the thyroid does not respond properly, failing to produce the necessary hormones.

So yes, hypothyroidism can negatively impact fertility. This condition leads to reduced ovarian hormone production and disrupts menstrual cycle regularity. In addition, insufficient thyroid hormones increase prolactin levels—a hormone that inhibits ovulation.

How Is Infertility Treated in Women with Hypothyroidism?

Women with hypothyroidism who are undergoing IVF or egg donation must also follow a specific treatment protocol:

Oral thyroid hormone tablets until TSH levels fall below 2.5
Periodic monitoring to determine whether the dosage needs to be adjusted

Is Hypothyroidism Hereditary?

It can be hereditary, particularly in cases of autoimmune hypothyroidism—when the immune system damages the thyroid gland, reducing hormone production. This is known as Hashimoto’s thyroiditis. The condition tends to occur more frequently in people with a family history of thyroid disorders.

Symptoms of Hypothyroidism

Common symptoms of hypothyroidism include:

Weight gain
Low libido
Muscle and joint pain
Constipation
Pale complexion and dry skin
Heavy menstruation and irregular cycles
Swelling in the face, hands, and feet

Notably, many women are unaware they have the condition. According to the Spanish Society of Clinical Biochemistry and Molecular Pathology, 7 in 100 people in Europe has a thyroid disorder, without being aware of it. Most of them are undiagnosed because the symptoms often mimic other conditions.

How Does Hypothyroidism Affect Female Fertility?

Some of the most important ways hypothyroidism affects female fertility include:

Irregular menstrual cycles: Caused by an imbalance in follicle-stimulating hormone (FSH) and luteinizing hormone (LH), both of which regulate the menstrual cycle. Hypothyroidism may also cause anovulation, or the absence of ovulation.
Hyperprolactinemia: Excess prolactin production interferes with ovulation and can cause menstrual dysfunction.
Endometrial receptivity: Thyroid hormones are essential for ensuring that the uterine lining (endometrium) is in optimal condition for embryo implantation.
Lower ovarian reserve and egg quality

How Is Male Fertility Affected by Hypothyroidism?

Although hypothyroidism affects men differently, it can still compromise their fertility. Key effects include:

Semen abnormalities: Hypothyroidism can negatively impact sperm motility, morphology, and concentration—making it harder for sperm to reach and fertilize an egg.
Reduced libido: Low thyroid hormone levels are linked to a decrease in sexual desire, reducing the chances of natural conception.
Erectile dysfunction: Several studies link thyroid dysfunction to erectile issues, further affecting male fertility.

What Steps Should You Take to Get Pregnant if You Have Hypothyroidism?

Important steps for managing hypothyroidism while trying to conceive include:

See an endocrinologist: Understanding your degree of hypothyroidism and current TSH, T3, and T4 levels is critical for determining the appropriate treatment.
Monitor your treatment: It’s essential to track hormone levels over time to adjust your medication if needed.
Maintain healthy habits: Avoid harmful substances like alcohol and tobacco. A balanced diet and regular physical activity can help improve fertility outcomes.

How Does Uncontrolled Hypothyroidism Affect Pregnancy?

If left untreated, hypothyroidism can lead to serious pregnancy complications, including miscarriage. Identifying and treating the condition before or early in pregnancy is essential.

Potential complications include:

Difficulty achieving pregnancy
Higher risk of miscarriage, especially in the first trimester
Low birth weight
Neurological delays in the newborn
Increased risk of developing high blood pressure during pregnancy

Conclusions

Hypothyroidism disrupts hormonal function and can affect fertility in both women and men.
It occurs when the thyroid gland doesn’t produce enough T4 and T3 hormones needed for metabolism.
Low thyroid hormone levels reduce ovarian function, alter menstrual cycles, and increase prolactin, inhibiting ovulation.
Hypothyroidism can be hereditary, especially in cases of Hashimoto’s thyroiditis.