Thyroid During Pregnancy: Causes, Symptoms, Risks And Diagnosis!

Thyroid diseases affect approximately 200 million people worldwide.¹ As one of the most common diseases, raising awareness about it is imperative, which is why May 25^th is marked as World Thyroid Day.²  Despite the fact that this illness is harmful to everyone, it is particularly important for women who suffer from thyroid during pregnancy to take better care of themselves. As even a little carelessness can harm not only the mother but also the baby. If you're a pregnant mom who may have a chance of developing thyroid diseases, worry not! In this blog, we will provide insights on the causes, risk factors, symptoms, and screening options related to thyroid health during pregnancy. 

Thyroid Gland: An Overview

To know how thyroid diseases may impact your health (especially during pregnancy), you first need to understand what “thyroid” is? Well, thyroid is a small gland, whose shape has a resemblance to butterfly.³ It produces various hormone that are necessary for metabolism, growth and development of your body.⁴ In addition, it plays an important role in maintaining multiple bodily functions by secreting “thyroid hormones” in the blood stream constantly.⁴

Thyroid hormones are extremely beneficial when the body needs an extra surge of energy to carry out a certain task. For example, the amount of thyroid hormones may increase when you're out in extreme cold or hot environments. Even during pregnancy, one may experience high levels of thyroid hormones.⁴

What Hormones Does Thyroid Produce?

Thyroid gland produces three hormones: triiodothyronine (T3), tetraiodothyronine (T4), and calcitonin. Iodine is a key component of all these hormones, so it is crucial to consume iodine-rich food to support thyroid hormone  production.⁴ Despite how useful the thyroid gland is, it still cannot assess how much thyroid hormone your body needs. This is where the pituitary gland comes in.⁴ The pituitary gland is a pea-sized organ located in the brain that helps regulate the production of thyroid hormones via the messenger hormone, called as TSH.⁵ In simpler terms, the pituitary gland signals the  thyroid gland about how much hormone should be secreted into the bloodstream.⁴

We hope that you now have a basic understanding of the thyroid gland and its hormones. Let's now take a look at the role of  thyroid during pregnancy.

Role Of Thyroid During Pregnancy

As it is evident that thyroid hormones play a significant role in your body’s development. It’s only natural that thyroid hormones have an even pivotal role in the development and growth of your baby’s brain and nervous system.⁶

During the first trimester (3 months) of pregnancy, your baby relies entirely on your thyroid hormones. Towards the end of the trimester, your baby develops its own  thyroid gland. However, this gland is not yet capable of producing sufficient thyroid hormones until around 18-20 weeks.⁶ Apart from this, pregnant women also tend to  experience increased thyroid hormone levels due to HCG (human chorionic gonadotropin hormone) and estrogen are two pregnancy- related hormones. ⁶

It must be noted that “healthy” pregnant moms could have a slightly enlarged  thyroid gland that could indicate the onset of potential  thyroid diseases.⁶ As swollen or enlarged  thyroid gland cannot be caught early on, during a physical examination, one can consider taking a proactive test! 

Since a pregnant mother’s body produces hormones for both baby and herself, it may become difficult to detect thyroid diseases. However, if one pays close attention to symptoms, they can help prevent the development of these diseases.

In the following section, we’ve briefly discussed two thyroid diseases, which could help you in avoiding a potential health risk during your pregnancy.

2 Prevalent Thyroid Diseases During Pregnancy

The following diseases can develop in anyone. However, the risk of developing thyroid diseases are particularly high in pregnant women due to the fluctuating thyroid hormone levels. 

Hyperthyroidism & Hypothyroidism

In hyperthyroidism, the  thyroid gland produces too much hormone which causes the body's metabolism to speed up.⁷  

In contrast to to hyperthyroidism, hypothyroidism is a condition in which the thyroid gland is unable to produce enough  thyroid hormones to meet the needs of the body.⁷ 

Causes Of Thyroid Diseases

Hyperthyroidism can be caused due to various reasons, some of which are given below:⁷ 

• Graves’ disease - It’s an autoimmune condition which triggers increased thyroid hormone growth⁶
• Thyroid nodules - Mass or growth of cells in  thyroid gland⁸
• Thyroiditis - In this condition, the thyroid gland swells up 
• Postpartum thyroiditis - A condition in which  thyroid gland swells up in women after they give birth
• Excess iodine - When the body receives excessive amounts of iodine
• Benign tumor - Presence of benign tumor in  thyroid gland

Apart from above, hyperthyroidism can also be caused due to excessive treatment of hypothyroidism (which can cause thyroid gland to start producing more hormones) through medication and goiter. Goiter occurs when the  thyroid gland enlarges in size. There are 3 variations of goiter, let’s have a glance at them:⁷

• Endemic goiter: It may develop in individuals who constantly consume a diet that is poor in iodine.
• Simple goiter: It occurs when the  thyroid gland does not produce enough thyroid hormones to meet the body's demand. Therefore, to meet the body's needs, the  thyroid gland expands in size in order to compensate for the body's  thyroid hormone needs .
• Sporadic goiter: The cause of this condition is unknown, although in some cases an association with lithium medications has been seen.

Likewise hyperthyroidism, hypothyroidism can also be caused by various conditions and factors, which include:⁶

• Hashimoto’s disease - It’s an autoimmune condition
• Iodine deficiency - Lack of iodine in body
• Congenital hypothyroidism - When  thyroid gland isn’t able to function properly since birth due to genetic mutations⁹
• Excessive treatment of hyperthyroidism through medication - When an individual takes too much of antithyroid medicine for treating hyperthyroidism¹⁰
• Removal of  thyroid gland - If  thyroid gland has been surgically removed
• Thyroiditis - In this condition, the  thyroid gland swells up

Symptoms Of Thyroid Diseases

Diagnosing hyperthyroidism solely through identifying symptoms is quite difficult, since its symptoms are similar to those that occur in a normal pregnancy. Some of these symptoms are:⁶

• Fatigue 
• Inability to bear heat 
• Increased heart rate
• Hand tremors
• Unusual weight loss or inability to achieve healthy pregnancy weight gain

When women experience low levels of thyroid hormones  during pregnancy, it can lead to hypothyroidism. It's interesting to note that the symptoms of hypothyroidism in pregnant women are the same as those of hypothyroidism in general. Pregnancy-related hypothyroidism is not connected with a specific set of symptoms.

 Some signs and symptoms of hypothyroidism are:⁶

• Acute constipation
• Difficulty in concentrating & problems with memory
• Extreme fatigue
• Inability to bear cold 
• Muscle cramps

Risks Of Thyroid Diseases

Thyroid during pregnancy could be managed easily. Though if not taken care of in time, hyperthyroidism increases the risks of the following in pregnant women (causing harm to both mother and baby):⁶

• Congestive heart failure
• Low-birth weight
• Miscarriage 
• Preeclampsia (condition leading to high blood pressure)
• Premature birth
• Thyroid storm (when thyroid symptoms worsens abruptly)

If left untreated, hypothyroidism poses health risks to both baby and the mother. Some of these risks include:⁶

• Anemia
• Congestive heart failure (in rare cases)
• Low-birth weight
• Miscarriage 
• Preeclampsia (condition leading to high blood pressure)
• Stillbirth

Diagnosis

For Hyperthyroidism

Diagnosis for hyperthyroidism may include various steps, such as:¹¹

• Physical examination - To check visible signs of hyperthyroidism like hand tremors. Also, to take a look at the reflexes, eye, skin and heartbeat, etc.
• Blood tests - To examine levels of thyroid hormones (T-3 & T-4) alongwith TSH (thyroid stimulating hormone) in blood.
• Radioiodine scan - It’s done in cases, when an individual has high levels of thyroid hormones in their blood test results. This scan helps in discovering how much amount of thyroid is being produced in the body. 
• Thyroid ultrasound - In this test, the presence of thyroid nodules are examined.

For Hypothyroidism

A typical diagnosis test for hypothyroidism requires assessment of thyroid hormones: T-3 & T-4 and TSH (thyroid stimulating hormone) in blood.¹¹

So far, we have learned everything about the  thyroid gland in relation to pregnancy, including causes, symptoms, risks, and diagnosis.  Also, we know that you are probably curious about how to screen for thyroid diseases. Well, don’t worry, we will be covering that in our upcoming section!

Final Thoughts!

Thyroid during pregnancy could be easily managed if one gets timely diagnosis, treatment and care. 

Though we hope that by reading this blog, you have gained a better understanding of how thyroid hormones impact your pregnancy. It’s important to note that thyroid diseases  can affect anyone, but taking care of one's health and consuming necessary nutrients can help prevent them.  In conclusion, we recommend proactive testing to both pregnant women and other individuals for keeping a better track of respective thyroid health!