How Hypothyroidism Affects Women’s Fertility

For many women silently grappling with inexplicable weight gain, fatigue, and other puzzling symptoms, the elusive culprit could be an underactive thyroid, a condition often overlooked in the realm of fertility struggles.  In fact, research has shown that hypothyroidism can have a significant impact on women's reproductive health and fertility.

From understanding the impact on reproductive hormones to decoding the often-missed signs, we explore which blood tests and other labs you should consider,  and lifestyle changes you can make to promote fertility and healthy thyroid function.

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Understanding Hypothyroidism

The thyroid gland, a butterfly-shaped organ that sits in your neck's front, plays a crucial role in your body's metabolism and hormonal balance.

Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormone. This can occur due to various reasons such as autoimmune disorders, iodine deficiency, or damage to the thyroid gland.

The hormones produced by the thyroid gland regulate your body's major functions, including heart rate, body temperature, energy levels, and the menstrual cycle. When the thyroid gland produces too little thyroid hormone, it causes a myriad of downstream effects, disrupting many other hormones.

Millions of women suffer from hypothyroidism, yet about 3 in 5 are unaware they have an issue, according to the American Thyroid Association.

Read: 5 Signs of Thyroid Problems in Women

Impact on Reproductive Hormones

Hypothyroidism can disrupt hormone balance by affecting the levels of estrogen, progesterone, and luteinizing hormone (LH), among others (1).

A healthy pregnancy also depends on normal thyroid function. Studies have shown that women with untreated hypothyroidism are at a higher risk of pregnancy complications such as gestational diabetes, preeclampsia, and preterm labor (2).

Hypothyroidism Increases Risk of Fertility Struggles

Hypothyroidism affects women's fertility by interfering with the menstrual cycle, ovulation, and implantation.

Hypothyroidism lowers the levels of two important thyroid hormones, T3 and T4, which can cause irregular menstrual cycles, anovulation (when the ovaries do not release an egg), and luteal phase defect (when the endometrium doesn't develop correctly to support implantation) (1). Hypothyroidism can also affect the quality of the cervical mucus, making it difficult for sperm to reach the egg (3).

Hypothyroidism is also much more common in women who have PCOS, further diminishing fertility and potentially harming ovarian function (4). 

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Subclinical Hypothyroidism: A Hidden Culprit for Fertility Woes

Subclinical hypothyroidism means that the thyroid hormone levels are within the “normal” range on lab tests, with thyroid-stimulating hormone (TSH) often elevated. Subclinical hypothyroidism indicates an early-stage thyroid dysfunction.

While subclinical hypothyroidism may not necessitate thyroid hormone replacement in the eyes of some conventional providers, it can still pose a threat to fertility (5).

Estimates suggest that 2% to 4% of non-pregnant women of childbearing age grapple with this subtle form of thyroid dysfunction (6). The prevalence might be even higher, emphasizing the need for vigilance in evaluating thyroid health in women seeking to conceive.

Read: 9 Must-Have Preventative Screenings Before Turning 40

Signs and Symptoms to Watch Out For

Women with hypothyroidism may experience a range of symptoms that can be easily overlooked or attributed to other factors. These include weight gain, fatigue, hair loss, dry skin, mood swings, and irregular periods. Some women may also notice changes in their basal body temperature (BBT) and cervical mucus, which can affect their ability to track ovulation accurately.

It is essential to pay attention to these signs and symptoms and consult with a healthcare provider if you suspect you may have an underactive thyroid. A simple blood test can confirm the diagnosis, and early detection can prevent further complications of thyroid disease down the road.

Read: Increase Your Chances of Conception with Acupuncture

Thyroid-Fertility Connection: Key Tests and Indicators

If you suspect that hypothyroidism might be affecting your fertility, you need to get a comprehensive thyroid evaluation. The standard lab tests for thyroid function are TSH, free T3, and free T4. However, these tests may not detect early stages of hypothyroidism or autoimmune thyroid disease like Hashimoto’s thyroiditis. Additional tests, such as thyroid antibodies, check for thyroid autoimmunity.

A comprehensive thyroid panel consists of five simple blood tests:

  • TSH
  • free T4
  • free T3
  • reverse T3
  • anti-TPO & anti-thyroglobulin antibodies

Most women will have had their TSH levels tested at some point, but this number alone can be misleading. Ruling out hypothyroidism based solely on a “normal” TSH may miss some cases of Hashimoto’s especially, because thyroid function can be erratic in the early stages. 

In early Hashimoto’s, TSH levels may appear normal at the time of a test, even if you have an underactive thyroid gland.

Related: Could PCOS Be Autoimmune?

Promoting Fertility and Thyroid Harmony

With treatment, you can work with your doctor to reduce the chances of related fertility issues down the line. In one group of almost 400 women suffering from infertility, 24% of participants were found to have hypothyroidism—but within a year of treatment, 76% were able to conceive (7). 

The thyroid is only one part of an interconnected web of glands and hormones that communicate with each other to maintain balance. So if your thyroid needs extra support, it’s important that you work to balance other hormonal issues as well.

If you end up needing thyroid treatment, its success is also dependent upon overall hormone balance.

  • Prioritize blood sugar balance and insulin sensitivity by avoiding sugary foods and choosing a balance of protein, healthy fats, and fiber during mealtimes.
  • Address your stress levels to balance adrenal hormones like cortisol. Chronic stress can suppress fertility hormones.
  • Consider getting tested for food sensitivities or allergies. Any kind of inflammatory response in the body can trigger thyroid problems and contribute to an autoimmune attack on the thyroid. Gluten is a common sensitivity with Hashimoto’s (8).
  • Gut health is also essential for proper thyroid function. The majority of the immune system resides in the gut, and inflammation or imbalance in this area can lead to autoimmune reactions.
  • Eat nutrient-dense foods that support thyroid function, including iodine-rich foods, selenium, and omega-3 fatty acids.
  • Adequate Sleep: Ensure sufficient and restorative sleep for hormonal regulation and thyroid health.

If you suspect that hypothyroidism might be affecting your fertility, getting a comprehensive thyroid evaluation is crucial.

Related: The Integrative Medicine Guide to Infertility

What to Remember

For women facing fertility challenges, a thorough exploration of thyroid function is pivotal. Seeking the guidance of a healthcare professional well-versed in thyroid health and fertility can pave the way for targeted interventions.

Unmasking hypothyroidism, whether overt or subclinical, and embracing lifestyle adjustments can not only enhance fertility prospects but also lay the foundation for a healthier thyroid and overall well-being.


Fertility, infertility, thyroid

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