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Thyroid disease during pregnancy: Causes, complications, and treatment

December 22, 2021 Posted in: Blogs


Optimal levels of thyroid hormones are necessary during pregnancy, assuring the baby’s healthy growth and development during the first three months. However, two pregnancy-related hormones—estrogen and human chorionic gonadotropin (hCG)—can cause thyroid imbalances in pregnant women. Keep on reading to learn more.

Thyroid and pregnancy complications

Thyroid disease is the second most common endocrine disorder that affects women of reproductive age. When thyroid disease is untreated during pregnancy, it can increase the risk of placental abruption, miscarriage, growth restriction, and hypertensive disorders.

What is placental abruption? A complication in pregnancy wherein the placenta detaches from the womb’s inner wall. This condition could deprive the baby of nutrients and cause vaginal bleeding, back pain, and belly pain in the mother.

There are two main kinds of thyroid disorders that occur during pregnancy.


Hyperthyroidism occurs when the thyroid gland is overactive, causing body functions to speed up. During pregnancy, hyperthyroidism is usually a result of Grave’s disease, an autoimmune disorder that causes the immune system to attack the thyroid gland, which retaliates by producing too many thyroid hormones.

Can pregnancy cause hyperthyroidism? Pregnant women who experience severe nausea, vomiting, or are carrying more than one infant may sometimes develop temporary hyperthyroidism or transient gestational thyrotoxicosis. This is a result of the overproduction of hCG.

Symptoms of hyperthyroidism during pregnancy include:

  • Hand tremors
  • Rapid, irregular heartbeat
  • Sudden weight loss
  • Severe nausea
  • Trouble sleeping
  • Heightened anxiety or nervousness

How can hyperthyroidism affect pregnancy?

Untreated hyperthyroidism during pregnancy can lead to premature birth, congestive heart failure, and low birth weight for the baby. Another side effect of hyperthyroidism during pregnancy is effects on the baby’s thyroid, making it overproduce thyroid hormones.


Hypothyroidism is when the thyroid gland is underactive and doesn’t produce enough hormones, causing a slowdown of bodily functions. When it occurs during pregnancy, it often comes as a result of Hashimoto’s disease, in which the immune system mistakenly damages the thyroid gland so it can’t produce enough hormones to meet the body’s needs.

Symptoms of hypothyroidism during pregnancy include:

  • Constipation
  • Sensitivity to cold temperatures
  • Muscle cramps
  • Memory problems or difficulty concentrating

How can hypothyroidism affect pregnancy?

Hypothyroidism can cause anemia, gestational hypertension, preeclampsia, or heart failure when left untreated. Hypothyroidism can also lead to problems with normal development for the baby if left untreated in the first trimester.

When to contact an endocrinologist

Higher thyroid hormone levels and shared symptoms with pregnancy make thyroid disorders challenging to diagnose in pregnant women. Unless you have prior history, are at high risk, or have symptoms of a thyroid condition, your thyroid will likely not be tested. Here are some risk factors to watch out for:

  • History of a thyroid condition
  • Family history of autoimmune disorders
  • Type 1 diabetes
  • Have had high-dose neck radiation treatment


Talk to a St. Joseph Health endocrinologist or primary care physician if you have questions or concerns about your thyroid or hormones before and during pregnancy. Your OBGYN can also refer you to a specialist if they suspect a hormonal problem.

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