Hypothyroidism and Pregnancy

Hypothyroidism is a common condition seen in women more than men. It means you have an under-active thyroid gland. The thyroid gland is a hormone gland. It is located in your neck in front of your windpipe. This gland is controlled by the pituitary gland in your brain. The pituitary gland produces thyroid stimulating hormone (TSH). TSH controls the amount of thyroid hormone (TH) produced by the thyroid gland. With hypothyroidism, the gland does not produce enough TH. The body needs this hormone for metabolism. Metabolism is how your body works and handles food.

A baby (fetus) needs to get thyroid hormone from the mother. It is needed for normal growth and brain development. Babies who are born to mothers with hypothyroidism during pregnancy may have lowered IQ scores. They may also have low birth weight or be born prematurely. Their body movement may develop poorly, too. Common problems during pregnancy are fatigue and weight gain. These symptoms may be hidden by the pregnancy. Hypothyroidism can develop before or during pregnancy.


  • Thyroid gland abnormality.

  • The pituitary gland in the brain produces too much TSH.

  • The most common cause before, during and after pregnancy is chronic (lasting) thyroiditis. It is an autoimmune condition that affects the thyroid cells. This is called Hashimoto's disease.

  • Surgical removal of the thyroid (thyroidectomy).

  • Radioactive iodine treatment of the thyroid gland that can destroy the gland. This is not used during pregnancy since it can affect the baby.

  • Lack of iodine in your diet. Most salt products contains iodine.

  • Women with Type 1 diabetes have a 5 to 8% chance of developing hypothyroid disease while pregnant. Type 1 diabetic women have a 25% chance of developing the disease after they have their baby.


Symptoms of hypothyroidism can develop slowly. They can go undetected if the symptoms are mild. This can be prevented with early detection in the pregnant mother. When you are pregnant, a mild form of hypothyroid disease can develop into a full blown disease because of an increase in the metabolism (destruction) of thyroid hormone in your body during pregnancy. If you are considering pregnancy, and you or an immediate family member have had problems thyroid problems, tell your caregiver. Make sure that you are watched closely as your caregiver suggests.

Some problems you may have before or during pregnancy are:

  • Constipation.

  • Fatigue.

  • Intolerance to cold.

  • Mental weariness.

More advanced problems with hypothyroidism may include:

  • Hoarseness.

  • Swelling of the lower legs.

  • Dry and thickened skin.

  • Slowness of thinking.

  • Decreased sex drive (libido).

  • Slowed speech.

  • Weight gain.

  • Muscle cramps.

  • Insomnia.

  • Slow reflexes.

  • Changes in your voice (deeper).

  • Puffy face and feet.

  • Thin, coarse hair.

  • Thinning of eyebrows.

  • Decreased appetite.

  • Increase incidence of carpal tunnel syndrome.

  • Coma.

Signs of Hypothyroidism include:

  • Enlarged thyroid gland (goiter).

  • Small round growths (nodules) in the thyroid gland.

  • Increase in thyroid stimulating hormone. (A blood test is needed.)

  • Decrease in thyroid hormone. (A blood test is needed.)

Common problems before pregnancy can include:

  • Inability to get pregnant.

  • Changes in menstrual periods.

  • No menstrual period (amenorrhea).

  • Miscarriage.

Common thyroid problems during or after pregnancy can include:

  • The development of high blood pressure and the chance of a premature delivery are more common.

  • Babies born to women with untreated hypothyroidism may not have good development of the brain.

  • Preterm delivery.

  • Low birth weight babies.

  • Preeclampsia.

  • Placental abruption.

  • Cretinism in baby (mental retardation, failure to grow, nerve (neurologic) and psychological problems).

  • Stillbirth.


Diagnosis is based upon the signs and symptoms of the patient. It is confirmed by blood tests ( increased TSH and decreased TH), ultrasound, and radioactive iodine uptake tests. The radioactive iodine uptake test is not done when you are pregnant. When hypothyroidism is diagnosed early, it can be treated. There should be no problems for you or your baby. Goiter or thyroid nodules found in a pregnant woman should be tested to be sure there is no cancer present. Anyone with a history or family history of thyroid disease should be tested for thyroid disease.


When hypothyroidism is diagnosed early, it can be treated. Treatment during pregnancy should not cause any harm to your baby.

  • Your caregiver will watch your thyroid hormones (TSH and TH) closely during the pregnancy.

  • Increase or decrease the dose of thyroid medication as your caregiver advises. This medicine is safe for you and your baby.

  • Avoid medications or supplements that can block the absorption of the hormone you are taking. For instance, calcium and iron are medications that may decrease the benefits of your thyroid medicine. Taking medications several hours apart will help this.

  • THS and TH should be checked each month of the pregnancy. At times, they should be checked more often in the third trimester.

  • All the states, including Washington, DC, offer screening tests for hypothyroidism in newborn babies.

  • If this disease is treated in the first few weeks after the baby is born, it can prevent abnormal growth and mental retardation. The pediatrician should be informed if the mother had hypothyroidism.


  • Avoid medications or supplements, such as calcium and iron, that can block the absorption of the hormone you are taking. If you must take these medications, take them several hours apart.

  • Pregnant women should take multivitamins that contain iodine. Your caregiver may suggest that you take 220mcg of iodine.

  • Women planning to get pregnant should take a multivitamin containing iodine. Your caregiver may suggest that you take 150mcg of iodine.

  • Include foods in your diet that contain iodine, such as iodized salt, spinach and shell fish.

  • Follow the advice of your caregiver regarding your medication and getting the necessary blood tests.

  • Get tested for thyroid disease before getting pregnant if you or someone in your family has had thyroid problems.

  • Get tested if you think you have symptoms of thyroid disease.


  • You have decreased or no movements of the baby.

  • You develop muscle cramps.

  • You have belly (abdominal) pain.

  • You gain too much weight in one week (5 pounds or more).

  • You develop a severe headache or vision problems.

  • You develop severe swelling of your legs and ankles.

  • You develop a lump in your neck.

  • You think you have symptoms of thyroid disease.


  • Understand these instructions.

  • Will watch your condition.

  • Will get help right away if you are not doing well or get worse.