Patient education: Hyperthyroidism (overactive thyroid) and pregnancy (The Basics)

What is hyperthyroidism? — Hyperthyroidism is a condition that can make your heart beat fast, or make you feel shaky or anxious. It involves a gland in the neck called the thyroid (figure 1). This gland makes thyroid hormone, which controls how the body uses and stores energy.

Hyperthyroidism is the term that doctors use when the thyroid gland makes too much thyroid hormone.

What if I have hyperthyroidism and want to get pregnant? — If you have hyperthyroidism and want to get pregnant, talk with your doctor or nurse before you start trying.

Your doctor will treat your hyperthyroidism before you start trying to get pregnant. In general, hyperthyroidism in a person who is not pregnant can be treated with:

●Medicines

●Radioiodine – This comes in a pill or liquid that you swallow. It contains a small amount of radiation.

●Surgery to remove part or all of the thyroid gland

You and your doctor will figure out which treatment is best for you. The decision depends on many factors.

It's best to treat your hyperthyroidism before you try to get pregnant. If your hyperthyroidism is treated, you won't have to take medicines for it during pregnancy.

If you get treatment with radioiodine or surgery, you will need to wait at least 6 months before trying to get pregnant. That way, your doctor will have enough time to check whether you are making enough thyroid hormone.

Many people treated with radioiodine or surgery make too little thyroid hormone after treatment. This is a problem because people with too little thyroid hormone can have trouble getting pregnant. Also, if you have too little thyroid hormone and do get pregnant, it can affect your baby's development early in pregnancy. People who don't make enough thyroid hormone will need treatment.

What if I develop hyperthyroidism during pregnancy? — If you develop hyperthyroidism during pregnancy, your doctor will want to know what's causing it. The 2 most common causes are:

●A condition called Graves' disease (figure 2)

●A condition called hCG-mediated hyperthyroidism – This is caused by a pregnancy hormone called hCG (human chorionic gonadotropin).

To figure out the cause, your doctor will do different blood tests.

How might hyperthyroidism affect a pregnancy? — Mild hyperthyroidism does not usually cause any problems for a pregnant person or their baby. But severe hyperthyroidism can lead to problems if it isn't treated. These can include:

●Problems in the mother, such as heart problems or a condition called preeclampsia

●Problems with the pregnancy, such as preterm labor (when labor starts too early) or pregnancy loss (miscarriage)

How is hyperthyroidism that develops during pregnancy treated? — Treatment depends on what's causing the hyperthyroidism and how serious it is.

●hCG-mediated hyperthyroidism does not usually need treatment. This condition usually goes away on its own later during pregnancy.

●Mild hyperthyroidism from Graves' disease also does not usually need treatment. But your doctor will monitor your thyroid hormone levels by doing blood tests regularly.

●Severe hyperthyroidism from Graves' disease does need treatment. This usually involves medicines called thionamides. Your doctor will prescribe different ones at different times during your pregnancy. That's because some are more likely to cause birth defects at certain times during pregnancy.

Will I need tests? — Yes. During pregnancy, you will have blood tests to check your thyroid hormone levels regularly.

If you have Graves' disease, you will also have tests to check whether your unborn baby has hyperthyroidism. Even though it is rare, unborn babies sometimes get hyperthyroidism. These tests usually include blood tests and an ultrasound. An ultrasound uses sound waves to create pictures of your baby. If your unborn baby has hyperthyroidism, the doctor can treat it by giving you medicine.

After pregnancy, people with Graves' disease will have blood tests to check their thyroid hormone levels every so often. That's because the condition can come back later.

Can I have a normal vaginal delivery? — Yes. Most people can have a normal vaginal delivery.

Can I breastfeed my baby? — Yes. Most people are able to breastfeed. But talk to your doctor so they can make sure your medicines are safe to take when breastfeeding.

Will my baby be healthy? — Chances are good that your baby will be healthy. In rare cases, though, babies born to mothers with Graves' disease can also have hyperthyroidism. To check for this condition, babies have blood tests after birth.

More on this topic

Patient education: Hyperthyroidism (overactive thyroid) (The Basics)
Patient education: Hypothyroidism (underactive thyroid) (The Basics)
Patient education: Graves' disease (The Basics)
Patient education: How to plan and prepare for a healthy pregnancy (The Basics)
Patient education: Prenatal care (The Basics)
Patient education: Preterm labor (The Basics)
Patient education: Pregnancy loss (The Basics)

Patient education: Hyperthyroidism (overactive thyroid) (Beyond the Basics)
Patient education: Hypothyroidism (underactive thyroid) (Beyond the Basics)
Patient education: Preterm labor (Beyond the Basics)
Patient education: Pregnancy loss (Beyond the Basics)