Thyroid disorders and fertility

Thyroid hormones have really important roles in your body, including metabolism, growth and development, digestion, mood, heart health and reproduction. Periods, menstrual cycles and ovulation are all controlled by these hormones and because of this, thyroid hormone imbalance can affect fertility in various ways.

Thyroid disorders can mean that your thyroid is either producing too much of the hormones (overactive thyroid, or hyperthyroidism) or not enough of the hormones (underactive thyroid, or hypothyroidism).

• Thyroid Stimulating Hormone (TSH): it is released from a part of the brain called the pituitary gland and it stimulates the thyroid gland to produce other hormones.

• Thyroxine (T4) and triiodothyronine (T3): T4 and T3 are produced in the thyroid gland.

What are the symptoms of thyroid imbalance?

Thyroid imbalance is really common and is caused by either an underactive thyroid (known as hypothyroidism) or an overactive thyroid (hyperthyroidism).

Can I still get pregnant with an overactive or underactive thyroid?

It is possible to get pregnant with an overactive or underactive thyroid when the thyroid imbalance is managed.  

Underactive thyroid can lead to irregular periods, lack of ovulation, and overall difficulty conceiving. It can also increase the risk of miscarriage if left untreated. However, with proper treatment, thyroid function can be restored to normal levels, improving your chances of conceiving and having a healthy pregnancy.

Overactive thyroid can also affect menstrual regularity and ovulation. In some cases, it can cause disappearance of periods, making conceiving really challenging. Moreover, if hyperthyroidism isn't treated, it can affect the womb environment, making it harder for an embryo to implant. 

Untreated or poorly managed thyroid disorders can also lead to increased risks during pregnancy, including miscarriage, preterm birth, preeclampsia, and developmental issues in the baby. 

A physical examination will be performed, to check if your thyroid gland is enlarged in the neck or whether you have any tremors. Finally, thyroid hormone blood tests will be done. Your doctor will check your TSH and T4 (and sometimes T3) levels, which will confirm whether your thyroid gland is functioning properly. As mentioned above, abnormally high levels of TSH and lower levels of T4 signal overactive thyroid, whereas very low levels of TSH and high levels of T4 mean your thyroid gland is underactive. 

If there’s any doubt, your doctor can refer you to have your thyroid gland checked by ultrasound. The sonographer will look at the size and structure of the thyroid gland and presence of any abnormalities. 

How are thyroid disorders treated?

If you have an underactive thyroid…

Lifestyle changes, such as adding iodine-rich foods (milk and dairy products), white fish, more eggs, beans, pulses or red meat to your diet can help your thyroid. Taking vitamin D supplements is also recommended during the cold season.

If lifestyle changes are not enough, you might be prescribed thyroid hormone replacement therapy medicines, such as levothyroxine, which will maintain your thyroid hormone levels within normal ranges. You will likely have regular blood tests to test your TSH and T4 levels.

If you have an overactive thyroid…

If your thyroid is producing too much hormone, your doctor might advise you to take antithyroid medicines, such as carbimazole, propylthiouracil or methimazole to decrease the function of your thyroid gland. Beta-blocker treatment can be prescribed to manage rapid heart rate, tremors and anxiety. 

Are these medications safe and do they make it harder to conceive? 

Thyroid medications are generally safe and can improve fertility for individuals with thyroid imbalances, provided they are taken as prescribed and monitored by a medical professional. 

If you have concerns about how thyroid medications might impact your fertility, discuss them with your doctor, who can provide personalised guidance based on your specific situation.