In pregnancy, hyperthyroidism is most often the result of Graves’ disease. If untreated, hyperthyroidism may cause serious complications like early labor and stillbirth.

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Hyperthyroidism in pregnancy is rare, affecting around 1–4 out of every 1,000 people during pregnancy. Early and accurate diagnosis and treatment are especially important for individuals with hyperthyroidism while pregnant to help avoid serious complications like premature delivery, maternal hypertension, and others.

Here’s what you need to know about having hyperthyroidism during pregnancy.

Learn more about hyperthyroidism.

Hyperthyroidism means that your thyroid is producing too much thyroid hormone. Excess thyroid hormone can speed up your body’s processes and stress your body.

In a pregnancy, the fetus relies on hormones produced by the mother’s thyroid for the first 18–20 weeks. Appropriate levels of thyroid hormones from the mother are crucial in developing the baby’s nervous system and brain. In later stages of pregnancy, excess thyroid hormones from the mother can lead to fetal hyperthyroidism and other complications.

Signs of hyperthyroidism in pregnancy can include:

  • an irregular or fast heartbeat
  • shaky hands
  • fatigue
  • anxiety and insomnia
  • unable to gain the expected weight or weight loss

Hyperthyroidism in pregnancy is most often the result of an autoimmune disease called Graves’ disease. Antibodies cause your thyroid to make additional thyroid hormones in individuals with Graves’ disease.

In rarer cases, extreme morning sickness (hyperemesis gravidarum) or thyroid nodules may be due to hyperthyroidism in pregnancy.

Individuals may be at a higher risk for hyperthyroidism during pregnancy if they have:

  • a prior thyroid condition they are receiving treatment for
  • previously had a thyroid condition during pregnancy
  • birthed a baby with a thyroid condition
  • an autoimmune disorder
  • type 1 diabetes

Potential complications of untreated hyperthyroidism during pregnancy for the mother include:

Complications in a baby may include:

Though it’s rare, unmanaged hyperthyroidism during pregnancy can result in a miscarriage or stillbirth.

Doctors prescribe antithyroid medications like propylthiouracil and methimazole to treat hyperthyroidism in pregnancy.

In rare cases where an individual is allergic to medications or goiters are present, surgery may be necessary, but in most cases, surgery is not preferred.

Cases of hyperthyroidism in pregnancy related to hyperemesis gravidarum may only require treatment for dehydration and vomiting.

Hyperthyroidismin pregnancy is considered a high risk situation. It’s important to monitor individuals with hyperthyroidism and their babies throughout the pregnancy and postpartum period.

Unmanaged hyperthyroidism can cause significant harm to mother and baby, so individuals with risk factors or who develop symptoms should be tested and begin treatment as quickly as possible.

If you have symptoms of hyperthyroidism, your doctor may perform a physical exam and run blood tests to determine the amount of thyroid hormones and thyroid-stimulating hormone.

To encourage good thyroid health during pregnancy, you’ll need to consume extra iodine. You should talk with your doctor to ensure that your diet and supplements offer the correct amount of iodine to support you and your growing little one.

Many of the genetic diseases and autoimmune disorders that lead to hyperthyroidism in pregnancy can’t be prevented. However, getting treatment for known conditions and making healthy lifestyle choices can help your overall health, including your thyroid.

Will hyperthyroidism improve after a mother gives birth?

Hyperthyroidism may not improve after the baby arrives. Women with Graves’ disease may see an improvement in the third trimester, but it may get worse again during the postpartum period.

Can a mother with Graves‘ disease nurse her newborn?

Many birthing parents can safely nurse their babies while on antithyroid medications, though some hormones can pass through breast milk. It’s always important to talk with your doctor about the safety of nursing when you are on medications.

Is an underactive thyroid (hypothyroidism) also dangerous in pregnancy?

Although hypothyroidism is the opposite of hyperthyroidism, if left unmanaged both can cause miscarriage or stillbirth. It’s important to talk with your doctor or midwife if you believe you have symptoms of either condition during pregnancy.

Hyperthyroidism means that your thyroid is producing too much thyroid hormone. In pregnancy, it is most commonly the result of Graves’ disease and can be diagnosed with blood testing.

If you have hyperthyroidism during pregnancy, treatment is essential to help prevent serious complications for you and your baby. It’s important to let your doctor or midwife know if you have any symptoms of hyperthyroidism.

After your pregnancy, you may still need medications to treat hyperthyroidism, depending on the cause.