The thyroid is one of your body’s most important endocrine glands that control the rate at which you produce and consume energy, in other words, your metabolism. The thyroid is under the direct control of the master gland called the pituitary present in the brain. The pituitary rereleases a hormone called thyroid-stimulating hormone (TSH). The TSH, in turn, stimulates the endocrine gland to release three hormones called triiodothyronine (T3), Thyroxine (T4), and Calcitonin. 

You might know that T3, T4, and TSH are vital in maintaining a healthy weight and overall mood. However, the same hormones can also affect your menstrual cycle and fertility. If you are trying to conceive, it is important to understand the role of the thyroid in controlling your fertility. 

Keep reading if you wish to learn more about the importance of the thyroid gland and how the hormones it produces can affect your fertility and influence your chances of getting pregnant. 

Thyroid Disorders and Fertility 

Different disorders affect more women than men. Women are more prone to developing thyroid-related diseases than men by a factor of 4-5. 

Hyperthyroidism

Hyperthyroidism is characterised by an elevation in the levels of hormones secreted by the gland. As many as 5% of all women are affected by hyperthyroidism. Some of the symptoms of this condition include:

• Unexpected weight loss
• Increased appetite 
• Feeling nervous and anxious
• Having trouble falling asleep
• Fewer menstrual cycles and lighter periods
• Increased sweating and intolerance to heat

Hypothyroidism

It is a condition that results in a decrease in hormones produced by the gland; in other words, the thyroid is underactive in such people. It is found in about 2-4% of women. Some of the common symptoms of hypothyroidism include the following:

• Unexpected weight gain
• Intolerance to cold
• Fatigue
• Thinning hair
• Pale skin
• Heavier menstrual bleeding

The symptoms of hypothyroidism are quite similar to polycystic ovarian syndrome (PCOS). As a result, your doctor might want to get tested for both PCOS and hypothyroidism if you present these symptoms. 

Unfortunately, doctors don’t proactively screen for thyroid issues in women who are not pregnant and not experiencing any symptoms under current medical practices. 

The Australian Thyroid Foundation recommends regularly checking your thyroid once you are 35. However, if any close relative in your family has thyroid disease, you might be susceptible to thyroid issues yourself. It is crucial to check your thyroid levels if you are experiencing any symptoms of hyper or hypothyroidism. 

Thyroid Dysfunction And Reproductive Health

The thyroid function is controlled by a combination of two glands: the hypothalamus and the pituitary. As both these glands are interconnected, they are sometimes called the Hypothalamic-pituitary axis (HPA). The hypothalamus stimulates other endocrine glands by releasing specific hormones that stimulate the pituitary, which releases another set of hormones that stimulate the other glands. 

The HPA also controls the production of hormones that impact fertility as well. Hence, a dysfunction of the thyroid gland can cause problems with fertility. The menstrual cycle events can have significant consequences if the hormones are out of sync. If your cycle is not regulated properly, there can be issues with ovulation, directly hampering your chances of getting pregnant. 

The hypo-secretion and hypersecretion of thyroid hormones have been connected with reproductive health and fertility as they can disrupt your menstrual cycles. 

Getting on top of any thyroid issues as soon as possible is crucial to prevent them from affecting your fertility over the long run. Fortunately, you can manage thyroid dysfunction easily using medications. 

Several studies have tried to understand the effect of thyroid dysfunction on infertility among women. One study on 400 women with infertility found that 24% of the fertility-issue participants also had hypothyroidism. The good news is that out of those women, around 76% could conceive within a year following regular treatment for hypothyroidism. 

‘Normal Range’ TSH levels and unexplained fertility problems

TSH, or thyroid-stimulating hormone, is a hormone secreted by the pituitary gland that stimulates the gland to release its hormones. People with low-functioning thyroid need a higher TSH level for stimulation and generally show an elevated TSH level. 

In some cases, the level of TSH is slightly elevated, but the thyroid functions normally. In other words, such people have what is called subclinical thyroid insufficiency. A study on women with unexplained infertility found them to have subclinical elevations in their TSH levels. 

From these observations, the researchers concluded that even if the thyroid insufficiency is mild and subclinical, it can still hamper your chances of getting pregnant. 

What about thyroid issues and male fertility?

The hormones T3 and T4 play a crucial role in the development and function of the primary sex organs of males, the testicles. Consequently, if there is an impairment in thyroid function, it can impact male fertility as well. 

Some of the issues that your male partner can face if he has thyroid dysfunction include:

• Changes in semen volume ejaculated
• Low sperm count
• Impaired sperm motility
• Changes in the shape and size (morphology) of the sperm

Fortunately, it is quite possible to reverse these effects of hypothyroidism in men just like in women: by taking medication. In most cases, fertility issues resolve once proper treatment ensues. 

The Thyroid While You Are Pregnant

Thyroid issues, if not treated before pregnancy, can have a negative impact. 

As the developing baby needs thyroid hormones for development and relies on the mother to supply them, it can stress the mother’s gland. If you already have dysfunction issues, pregnancy can aggravate the symptoms. 

Thyroid hormones are crucial for the neurologic development of the foetus. If the mother has fewer thyroid hormones or antibodies (due to autoimmune diseases), the foetus might have issues in brain development. The good news is that T4 supplements (Levothyroxine) can significantly reduce the chance of your baby having any significant problems. 

The evidence of hypothyroidism causing miscarriages or loss of pregnancy is not robust. However, according to one study, hyperthyroidism can double the risk of miscarriages in women. One of the reasons for this finding was that the excess thyroid could be detrimental to the survival of the growing foetus. A few studies have also found a link between infertility and miscarriages with untreated hypothyroidism. 

Once you give birth, there is a risk of developing thyroiditis or inflammation of the thyroid. The frequency of this happening is 5-10% within the first year of giving birth. The inflammation can cause both hypothyroidism and hyperthyroidism. 

Treatment of thyroid disorders

It is crucial to get any issues under control if you plan to conceive to reduce the risk of complications during pregnancy. The treatment of hyperthyroidism and hypothyroidism can vary significantly depending on many factors, including the severity of the condition. However, both requirements can be managed with medications rather easily. 

It is important to titrate the medications’ doses during the treatment’s initial phase. Expect to get your blood drawn to test the hormone level every six weeks. Once the levels of thyroid hormones are stabilised in your body, a maintenance dose is selected that you will have to stick to for the remainder of the treatment period. You must also take yearly thyroid function tests to ensure the treatment effectively manages the condition. 

Fertility Issues & When To Get Checked

The first and foremost thing we learn from all this is the importance of the thyroid and its hormones. As thyroid function is not routinely checked, any dysfunction can go unnoticed for quite a long time. If you are trying to conceive, check your thyroid, especially if you have irregular periods or any issues related to the menstrual cycle. Talk to your doctor and get things under control before you try to get pregnant. 

A healthy endocrine system is essential for your reproductive health and improving your chances of conception. Consult your healthcare provider if you have any issues regarding your periods, such as irregularity, excessively heavy periods, or pain that does not seem normal.