Pregnancy & Thyroid Disease

Why are women more likely to get thyroid disease?

In general, women are much more likely than men to become hyperthyroid or hypothyroid and to get Hashimoto’s thyroiditis. The reason for this is uncertain.

Women are also more vulnerable to autoimmune diseases. Two of the most common thyroid diseases, Hashimoto’s thyroiditis and Graves’ disease, are caused by problems with the body’s immune system. Normally, the immune system defends the body against germs and viruses. In autoimmune diseases, the system attacks the body’s own tissues. Diseases of the immune system tend to run in families.

What about thyroid disease and pregnancy?

Hyperthyroidism or hypothyroidism can affect a woman’s ability to become pregnant. They may also cause a miscarriage if they are not quickly recognized and properly treated.

Women who become pregnant may not notice signs of thyroid disease because similar symptoms can occur in a normal pregnancy. For example, patients may feel warm, tired, nervous, or shaky. In addition, enlargement of the thyroid (goiter) commonly occurs during pregnancy.

A pregnant woman is treated differently than is a non-pregnant woman or a man. For example, radioactive materials commonly used in diagnosing and treating many thyroid diseases are never used in pregnant women. The timing of a biopsy or surgery for a thyroid nodule and the choice of drugs for hyperthyroidism may be different in a pregnant woman. These issues require careful consultation with your doctor.

What is postpartum thyroiditis?

Postpartum thyroiditis is a temporary form of thyroiditis. It occurs in 5%-9% of women soon after giving birth (postpartum period). The effects are usually mild. However, the disease may recur with future pregnancies.

The symptoms usually last for six to nine months. First, the damaged thyroid gland may release its stored thyroid hormones into the blood, causing hyperthyroidism. During this time, you can develop a goiter, have a fast heart rate, and feel warm or anxious. Then, a few months later, you will either return to normal or become hypothyroid. Hypothyroidism occurs because the thyroid has been damaged and its hormone reserves used up. If this happens, you may feel tired, weak, or cold. The hypothyroidism usually lasts a few months until the thyroid gland completely recovers. Occasionally, the hypothyroidism may be permanent.

How do doctors test for thyroid disease during pregnancy?

As with any disease, it is important that you watch for the early warning signs of thyroid disease. However, only your doctor can tell for sure whether or not you have the disease. Your doctor may examine:

  • your history and physical appearance
  • the amount of thyroid hormones, thyroid stimulating hormone (TSH), and thyroid antibodies in your blood.

How is thyroid disease treated during pregnancy?

Pregnancy places some limits on the treatments which you can receive, because your doctor must also look out for the safety of your child. A common treatment for hyperthyroidism is radioactive iodine, but it must be avoided by women who are pregnant or nursing a baby. Surgery to remove a goiter or cancer may also be delayed until after the pregnancy. However, needle aspiration biopsy of a thyroid nodule may be safely done during pregnancy.

Treatments which may be used for thyroid disease during pregnancy include:

  • antithyroid drugs, which block the production of thyroid hormone
  • thyroid hormone pills, which provide the body with the right amount of thyroid hormone when the gland is not able to produce enough by itself.

Postpartum thyroiditis may or may not be treated during the hyperthyroid stage, depending upon its severity. If the patient later becomes hypothyroid, her doctor may prescribe thyroid hormone pills.