Thyroid Disease in Pregnancy: Things You Need to Know


In a usual scenario, as soon as your pregnancy is confirmed by your doctor, you will be asked to take a thyroid test. You may also have to take one in case you are planning to conceive. Although thyroid during pregnancy is a common issue, it can be confused with other regular pregnancy symptoms due to its similarities. Symptoms like weight gain, feeling tired, getting moody or forgetful and even swelling up are common to pregnancy as well as a thyroid condition. In this article, we will discuss the details of thyroid disease in pregnancy. Read on to find out everything that you need to know about thyroid in pregnancy.

The thyroid problem during pregnancy is common when a woman is in her prime childbearing age, but if it is not diagnosed in time, its impact can extend well beyond pregnancy. While hyperthyroidism is caused due to high levels of hormones in the blood, hypothyroidism is caused due to decreased levels of thyroid hormones in the blood.

In this article:

How Do Pregnancy Affect Thyroid Functions?
Hyperthyroidism in Pregnancy
Hypothyroidism in Pregnancy

A Guide for Thyroid Disease in Pregnancy

How Do Pregnancy Affect Thyroid Functions?

During pregnancy, two hormones, oestrogen and human chorionic gonadotropin (hCG) are responsible for enhancing your thyroid levels. These thyroid hormones play a vital role when you are pregnant, both in the baby’s brain and nervous system development and your health.

The placenta makes hCG, which is similar to TSH and stimulates the thyroid to create more hormones. An increase in oestrogen levels produces thyroid-binding globulin, a protein that helps the thyroid hormone to travel in the blood. In the first trimester, your baby is dependent on you for its thyroid hormone needs, which comes through the placenta. This will go on until the 12th week, after which the baby’s thyroid will begin functioning on its own.

pregnancy and thyroid

It is necessary to conduct a thyroid function test to detect any pregnancy problem due to thyroid. However, these hormonal changes may go undetected and can be difficult to interpret despite these tests. The thyroid does increase in size during pregnancy, but this is not enough to be seen in the test. Thyroid related issues may be difficult to diagnose during pregnancy due to mutual signs increased thyroid hormone level, fatigue, and an increase in the size of the thyroid.

Hyperthyroidism in Pregnancy

When an overactive organ produces thyroid hormone in large quantities, the condition is known as hyperthyroidism.


Hyperthyroidism is usually caused by Grave’s Disease which is an autoimmune disorder in which the immune system attacks its cells and organs instead of protecting it. Toxic Adenomas is also the cause during which nodules that grow in the thyroid gland begin secreting hormones. This disturbs the body’s chemical balance.


Fatigue, Nausea, vomiting, fast heart rate, change in appetite and growth of thyroid levels and thyroid size are the typical symptoms of hyperthyroidism. One can also notice changes in appetite and lower tolerance to heat.


Treatment is not required for mild hyperthyroidism where TSH levels are low but free T4 is normal. In case of a severe thyroid disorder, the doctor prescribes propylthiouracil (PTU), in low doses during the first trimester. Anti-thyroid medication, methimazole is prescribed after the first trimester if necessary. In rare cases where the patient does not respond to medication, surgery may be suggested to remove a portion of the thyroid. Radioactive iodine treatment is not recommended for pregnant women since it can damage the baby’s thyroid gland.

Hypothyroidism in Pregnancy

The deficiency of thyroxin, the thyroid hormone, which occurs due to an underactive thyroid gland is known as hypothyroidism.


Low levels of thyroid hormones in the blood are the cause of this condition, where the thyroid gland functions inadequately. Removal of the thyroid, endemic goitre, iodine deficiency, radiation therapy and diseases related to the pituitary gland are its other causes. Hypothyroidism in pregnancy is also caused due to Hashimoto’s disease, which is a form of inflammation of the thyroid.


Common symptoms of hypothyroidism include a swollen face, fatigue, intolerance to cold, weight gain, lower concentration levels, skin tightening or stretching and abdominal discomfort. Decreased levels of T4 and high TSH levels are indicators of hypothyroidism too.


During pregnancy, Hypothyroidism is treated by starting on thyroxin, a synthetic thyroid hormone. Thyroxin is beneficial for the mother and the child and is safe too. Women who have developed this condition before pregnancy should increase their dosage after speaking to their doctor, to maintain thyroid function.


Your thyroid controls every cell in your body, and without its presence, the body slows down resulting in fatigue, weight gain, hair loss and much more. Here is how you can prevent thyroid and pregnancy complications from affecting your body and the baby:

  • Stay away from diets that recommend starvation for long periods. Fasting results in a huge reduction of T3 levels which enhances metabolism.
  • The thyroid gland is susceptible to x-rays. Make sure you ask for a thyroid shield whenever you undergo radiation during pregnancy.
  • If you are pregnant and have been smoking, it is time to stop. Those with a predisposition for thyroid are at higher risk. Smoking increases the risk of hypothyroidism especially for patients with Hashimoto’s thyroiditis.
  • To reduce the effect of thyroid on pregnancy, women with borderline hypothyroid should begin with a low dose thyroid hormone at the beginning of pregnancy.

Therefore, to conclude, it is necessary to keep reviewing the symptoms of hyper and hypothyroidism during pregnancy for which repeated testing of TSH levels is needed. Speak to your doctor if you observe any symptoms so that precautionary measures can be taken. By checking your thyroid levels, you can look forward to safe and hassle-free pregnancy.


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