Home » Hypothyroidism And Pregnancy
Issues Lifestyle Pregnancy

Hypothyroidism And Pregnancy

portrait of adorable pregnant woman in white. in love

Understanding The Effects Of Hypothyroidism During Pregnancy

Even though pregnancy is seen as a wonderful time in a woman’s life, there are many concerning factors that need to be accounted for. Before a woman can become pregnant, she needs to ensure that there are no issues with her fertility and also ensure that no underlying health problems may cause complications during pregnancy.

While pregnant, a woman needs to stay healthy and cater toward the wellbeing of both her own body and the growing baby inside of her.

The thyroid gland plays a particular role in both fertility andin pregnancy, yet many women fail to realize this. This gland is part of the endocrine system and secrets hormones known as Thyroxine and Triiodothyronine1, which plays a vital role in the metabolism of all cells found in the human body. These hormones do not only play a role in the woman’s body, but also for a baby during the course of pregnancy in a woman.

In this article, we’ll take a closer look at how Hypothyroidism, a condition that affects the production of Thyroid hormones by the Thyroid gland, can affect pregnancy.

We will consider the role of Thyroid hormones before pregnancy and also look at how an inadequate supply of Thyroid hormones can affect the outcome of pregnancy.

What Is Hypothyroidism?

The Thyroid gland is located in the neck and forms part of the endocrine system within the human body. This gland produces two hormones that contribute to overall metabolism within the body. Every cell in the body has a receptor that responds to these hormones.

When the Thyroid is unable to produce enough hormones to support the bodily functions that depend on these hormones, then they have developed a condition known as Hypothyroidism.

Hypothyroidism has numerous causes, with an autoimmune reaction being amongst the most common. Hashimoto’s disease is the leading cause of Hypothyroidism in the United States2, which is a condition that refers to an immune reaction where cytokines (cells of the immune system) starts to attack the Thyroid gland, even though the tissue of this gland is healthy.

Hashimoto’s disease is not the only factor that can cause Hypothyroidism. Other possible causes3 include:

  • Having the Thyroid or part of the gland removed through a surgical procedure, which may be necessary in the case of Thyroid cancer.
  • Undergoing radioactive iodine therapy as a treatment protocol for Thyroid cancer.
  • Some medication may cause the function of the Thyroid to become impaired, including Amiodarone, Interferon-alpha agents, Interleukin-2 agents, and Lithium.
  • Undergoing treatment for Hyperthyroidism (anti-thyroid medication is given to these patients) may lead to Hypothyroidism if the dosage is too strong.
  • Issues with the Pituitary gland, another part of the endocrine system that signals the Thyroid to produce hormones, can also cause inadequate amounts of Thyroid hormones to be released.

Symptoms Of Hypothyroidism That Should Not Go Unnoticed

All studies related to the prevalence of Hypothyroidism usually find that this condition is far more prevalent in women than it is in men4. This makes it especially important for women who are thinking of becoming pregnant and those already pregnant to recognize the symptoms of Hypothyroidism, as well as to obtain regular screenings to detect the condition early on.

Common symptoms that usually become present when Hypothyroidism develops are mostly related to the reduction in metabolism caused by an insufficient supply of Thyroid hormones. These symptoms may include5:

  • Fatigue and an overall feeling of weakness.
  • Blood pressure levels may become elevated.
  • Body weight may increase unexpectedly.
  • A reduction in sweating.
  • A higher sensitivity to low temperatures.
  • Cognitive impairment, such as a slow down in thoughts, problems remembering information and concentration-related issues.

Hypothyroidism And Fertility

To understand the connection between Hypothyroidism and pregnancy, we really have to start by looking at how this condition may have an impact on a woman even before she becomes pregnant. Fertility is a very important element that plays a role in a woman’s chance of becoming pregnant after conceiving. Many factors can have a significant impact on a woman’s fertility.

One study6 found that as much as 12.5% of women may be infertile, which means they are unable to become pregnant.

Some studies have been conducted and proven that a connection exists between different types of Thyroid diseases and infertility. One publication7 explains that, in 2015, an official study provided evidence that a definite connection exists. It was found that there is a higher prevalence of infertility in women who have been diagnosed with Hypothyroidism, as well as other types of Thyroid diseases, as compared to the general population.9

While further research still needs to be conducted in order to provide more accurate details on this connection and to allow people to understand how exactly Hypothyroidism may cause infertility, the data presented here means women should obtain more frequent tests to determine their Thyroid hormone levels.

Women who are finding it difficult to become pregnant are also advised to obtain blood tests to determine the levels of Thyroid hormones in their blood, as problems with their Thyroid gland might be to blame for their infertility.

Hypothyroidism And Pregnancy

Hypothyroidism does not only play a part in fertility but may also have an adverse impact on the outcome of pregnancy. Pregnant women are advised to be wary of the fact that an underactive Thyroid can deprive the growing child inside of their womb of essential hormones that are needed for optimal development, especially during the first few stages of pregnancy.

A number of possible complications have been linked to inadequate levels of Thyroid hormones in a woman’s body while she is pregnant. Such complications may include:

  • Premature birth
  • Miscarriage
  • Abruptio placentae
  • Postpartum hemorrhage
  • Preeclampsia
  • Anemia

While Hypothyroidism does not guarantee that a woman will experience any of these complications, it does provide for a significant increase in the risk. Reducing the risk of complications during pregnancy is vital for all woman, as this can lead to a more successful outcome – ensuring the child can be healthy once born.

One particular factor to consider about an underactive Thyroid is that the condition can become worse during pregnancy if not diagnosed and treated before a woman becomes pregnant. When pregnant, a woman’s body will require a larger amount of Thyroid hormone to assist with the development of the fetus, as well as to ensure additional requirements within the woman’s own metabolic functions can be met.

A healthy Thyroid is able to adapt according to these changes and naturally produce more hormones. When Hypothyroidism is present, however, the Thyroid hormones may decline even further with pregnancy, instead of increase to meet the needs for the excess amounts of Thyroid hormones8.

This is also where another complex problem comes into play. Many symptoms that a woman experiences during pregnancy can be similar to the symptoms associated with Hypothyroidism. For this reason, a woman with undiagnosed Hypothyroidism may not be concerned about symptoms that they experience. She may consider these symptoms a normal part of her pregnancy.

In such a case, Hypothyroidism may continue to impact her pregnancy and, in turn, cause an increased risk for pregnancy complications to develop.

For this reason, women who find that the symptoms they experience during pregnancy seem more significant and troublesome than what they should expect should consider seeing a doctor.

Testing for Hypothyroidism is a simple process and can help to detect this condition early on, which would lead to early treatment and a significant reduction in their symptoms, as well as a lower risk of experiencing complications with the pregnancy.

Treating Hypothyroidism To Reduce Complications With Fertility And Pregnancy

The treatment for Hypothyroidism is relatively simple for most, and most women will be happy to learn that the drugs used to treat this condition does not pose any threats to their pregnancy.

In fact, with the right dosage of the drugs used to treat Hypothyroidism administered, a woman may experience improvements in their fertility and also a lower risk of complications developing while she is pregnant.

The most common treatment option for Hypothyroidism is to provide the patient with Thyroid Hormone Replacement drugs.

These drugs contain synthetic Thyroid hormones that replace the missing hormones in the patient’s body; thus assisting the body in the functions that depend on Thyroid hormones to execute effectively. In most cases, the patient is provided a drug that contains a synthetic type of Thyroxine.

Thyroxine is also known as T4, and the body converts this Thyroid hormone into T3 or Triiodothyronine. It is important to note that the synthetic Thyroxine will work similar to how the naturally-produced Thyroxine hormones work when produced by the Thyroid.

Before synthetic Thyroxine drugs can be prescribed to a patient, a blood sample first needs to be taken to determine the levels of Thyroxine currently present in their blood.

Such a test will help the prescribing physician determine the most appropriate dosage the patient needs to take in order to restore optimal levels of this hormone in their bodies.

When treatment is administered to a patient before she becomes pregnant, then her fertility rate may be boosted, and she will also be less likely to experience complications with her pregnancy later on. If the condition is only detected while the woman is pregnant, then the treatment will help to support increased metabolic functions, as well as fetal growth, by supplying the body with extra Thyroxine hormones.

Thyroid Hormone Replacement drugs usually need to be adjusted during pregnancy and once again after the woman has given birth. This is because, after giving birth, metabolism slows back down to the rate it was at before the woman gave birth. For this reason, a higher dose of Thyroid Hormone Replacement drugs is often provided to a woman while she is pregnant.

After the birth of her child, the dosage is often lowered in order to avoid the development of Hyperthyroidism.


Hypothyroidism is a relatively common condition where the Thyroid fails to produce enough hormones to support the metabolism of the body at a cellular level. Untreated, this condition may yield problems for a woman who is trying to become pregnant.

Prior to pregnancy, the condition can cause fertility-related problems, and once pregnant, the woman may experience complications with her pregnancy.

Fortunately, treatment to restore normal levels of Thyroid hormones is readily available, which can help to reduce the risk of such complications and also aid in restoring optimal fertility in the woman.


1 Medical Definition of Thyroid hormones. MedicineNet.com. https://www.medicinenet.com/script/main/art.asp?articlekey=5780

2 Hashimoto’s disease. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/hashimotos-disease/symptoms-causes/syc-20351855

3 E. Berber. Causes of Hypothyroidism. EndocrineWeb. https://www.endocrineweb.com/conditions/hypothyroidism/causes-hypothyroidism

4 M.P.J. Vanderpump. The epidemiology of thyroid disease. Oxford Academic British Medical Bulletin. 1 September 2011. https://academic.oup.com/bmb/article/99/1/39/298307

5 Hypothyroidism: Symptoms. PubMed Health. https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0022777/

6 Multiple Authors. Prevalence of infertility and help seeking among 15 000 women and men. Oxford Academic: Human Reproduction. 19 August 2016. https://academic.oup.com/humrep/article/31/9/2108/2913864

7 R. Preidt. Thyroid Trouble May Harm Women’s Fertility: Study Finds. WebMD. 26 January 2015. https://www.webmd.com/infertility-and-reproduction/news/20150126/thyroid-trouble-may-harm-womens-fertility-study-finds#1

8 They Thyroid and Pregnancy. Thyroid Awareness. http://thyroidawareness.com/the-thyroid-and-pregnancy

9  Thyroid and Fertility Relationship. Thyroid Advisor. https://thyroidadvisor.com/thyroid-and-fertility-relationship/

Like what you read?

Subscribe to our mailing list and get interesting stuff and updates to your email inbox.

Thank you for subscribing on Thyroid Central.

Something went wrong.

What do you think?

About the author

Thyroid Central

Thyroid Central is a free resource with a wealth of information and breaking news about thyroid health and other health and lifestyle issues.