How your thyroid could impact your fertility

An estimated 1 in 8 women will develop thyroid disease within their lifetime.
Written by
Team Kin
Reviewed by
Last updated on
April 29, 2024
min read
How Your Thyroid Could Impact Your Fertility | Kin Fertility
Jump to:
Arrow Down

When it comes to fertility, there are a lot of factors to consider, and one of the biggest isn’t exactly the most obvious. In fact, the key to some fertility problems may actually be in your throat.

The thyroid, a butterfly-shaped organ at the front of the throat, plays a key role in menstruation, conceiving, and ovulation [1].

Whether trying to conceive, already pregnant, or just becoming more aware of your own fertility, paying attention to thyroid health can be a critical component in tracking and improving fertility.

How your thyroid can impact your fertility and pregnancy

“Thyroid hormones are essential in the first 12 weeks of embryo development,” says Dr Vedrana Högqvist Tabor, PhD, CEO of Boost Thyroid.

“The embryo can’t produce any thyroid hormones on its own just yet, but even in the later stages of pregnancy the mother’s thyroid hormones will impact the growth of the fetus.”

The thyroid is part of the endocrine system, which helps to both produce and distribute hormones throughout the body. Those hormones called T3 and T4, control the speed at which the body’s cells work.

This process is known as metabolic function, and if it isn’t working properly it can affect the body in a lot of different ways. When the thyroid doesn’t work properly it can cause problems with breathing, heart rate, muscle strength, body temperature, and the menstrual cycle.

The pituitary gland, an endocrine gland at the base of the brain that secretes hormones into the bloodstream, produces Thyroid Stimulating Hormone (TSH), which tells the thyroid to produce T3 and T4, the hormones that affect the speed of metabolic function.

It also releases prolactin, which stimulates lactation and affects the production of estrogen from the ovaries. If the thyroid and pituitary gland aren’t able to communicate properly because of a lack of, or an increase in, TSH or T3 and T4, the reproductive system can be affected.

An estimated 1 in 8 women will develop thyroid disease within their lifetime [2].

Given the thyroid’s direct connection to reproductive health, it’s important to understand and pay close attention to thyroid health, along with fertility, for a better chance of conceiving and an overall healthy pregnancy.

“Knowing your thyroid status can be really helpful for the reproductive specialists you work with,” says Dr Högqvist Tabor. “It is a crucial part of making informed decisions throughout the stages of a reproductive treatment journey.”

If the thyroid isn’t working properly, it is due to either hypothyroidism or hyperthyroidism.

Although just a few letters apart and extremely easy to mess up with autocorrect, the two affect the body very differently and both can impact fertility and pregnancy.

What is hypothyroidism?

Hypothyroidism happens when you have an underactive thyroid gland, meaning it doesn't produce enough thyroid hormone.

The symptoms of hypothyroidism can mirror those of normal pregnancy changes, such as weight gain, mood swings, and fatigue.

Hypothyroidism has been linked to maternal anaemia, myopathy, congestive heart failure, preeclampsia, placental abnormalities, and postpartum hemorrhage [3]. Pregnancy, and a change in hormones, can also trigger hypothyroidism in patients who were not previously diagnosed.

What is hyperthyroidism?

Hyperthyroidism is the opposite of hypothyroidism and is caused when you have an overactive thyroid, meaning it produces too much of the hormone thyroxine.

Hyperthyroidism has been linked to early labour, pre-eclampsia and thyroid storm — a possibly life-threatening condition that causes the heart rate to increase dangerously high [4].

It can also cause irregular menstrual periods, which can result in missed ovulation.

If uncontrolled, autoimmune thyroid disease can also lead to miscarriage and infertility. Too much or too little T3 and T4 can cause low success of fertilisation and embryo implantation and disturb typical embryo growth.

How do you diagnose thyroid disease?

Thyroid disease shares symptoms with several other conditions, which makes diagnosis difficult.

However, if your doctor suspects you may have hypo or hyperthyroidism, they may perform a number of tests [5]:

  • Blood tests to measure the thyroid hormone levels in your blood and see if you need to undergo further tests.
  • Imaging tests, or thyroid scans, to check if the shape, size or position of your thyroid gland has changed.
  • Physical exams where the doctor feels your neck to check for any growths.

Can you treat thyroid disease?

Hypothyroidism is typically treated with thyroid hormone replacement therapy, which is usually in pill form and works by compensating for the lack of hormones your thyroid gland is able to produce [6].

Note that this medication doesn't cure, but rather helps to manage hypothyroidism, so you'll most likely have to take it for the rest of your life.

As for hyperthyroidism, there are a few treatment options, including anti-thyroid drugs, beta-blockers, radioiodine therapy and, in rarer cases, thyroidectomy, which is a surgery to remove part of or the entire thyroid gland.

Thyroid and male fertility: Is there a link too?

It isn’t just women whose reproductive health can be affected by thyroid disorders.

Male fertility can also take a hit if the thyroid function isn’t working properly. Thyroid disease can lower testosterone, decrease sperm motility, and cause low counts of high-quality sperm.

Can you get pregnant with a thyroid disorder?

With close monitoring and treatment, a healthy pregnancy is totally possible for patients with an over or underactive thyroid.

Thyroid dysfunction patients should talk early and often with their endocrinologist about their plans to conceive, and how the dysfunction may affect their reproductive health.

It can be helpful to test your thyroid health when planning to fall pregnant to confirm you have normal thyroid function.

The most important thing to keep in mind is that you can get pregnant even if you struggle with thyroid issues.

All of the tools you need to take your reproductive health into your own hands.