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Everything You Should Know About Hypothyroidism in Pregnancy

hypothyroidism in pregnancy

Thyroid hormones affect practically every organ in the body and govern metabolism and the way the body uses energy. Hypothyroidism is caused by a lack of thyroid hormones, which can cause various biological functions to slow down. Hypothyroidism affects three to ten percent of adults, with women and the elderly having a higher incidence. Thyroid hormone is necessary for the development of a healthy infant as well as the mother’s health during pregnancy.

What Is the Thyroid?

The thyroid gland is a butterfly-shaped gland that is 2 inches long and weighs 25 to 30 grams in adults (it is slightly heavier in women). It has two lobes, one on each side of the trachea, and is located at the front of the neck below the larynx or voice box. Hormones are produced, stored, and released by the thyroid gland into the bloodstream. Hormones then flow throughout the body, controlling the activity of cells. Thyroid hormones triiodothyronine (T3) and thyroxine are produced by the thyroid gland (T4). T4 is converted into T3, which is the active hormone. Thyroid hormones regulate respiration, metabolism, brain growth, heart and nerve function, muscle strength, body temperature, menstrual cycles, dry skin, weight, and cholesterol levels. The pituitary gland in the brain produces thyroid-stimulating hormone (TSH), which regulates thyroid hormone production. The pituitary gland produces more TSH when thyroid hormone levels in the blood are low. The pituitary gland responds by lowering TSH production when thyroid hormone levels are high.


Thyroid hormone is necessary for a baby’s brain and nervous system to develop normally. The foetus relies on the mother’s supply of thyroid hormone, which flows through the placenta, during the first trimester. The baby’s thyroid begins to work on its own around the age of 12 weeks. In healthy women, the thyroid enlarges somewhat during pregnancy, but not enough to be noticed by a physical exam. Thyroid disease can be detected by a notably enlarged thyroid, which should be investigated. Due to higher amounts of thyroid hormones in the blood, increased thyroid size, exhaustion, and other symptoms common to pregnancy and thyroid diseases, thyroid abnormalities can be difficult to diagnose during pregnancy. Human chorionic gonadotropin (hCG) and oestrogen, two pregnancy-related hormones, produce elevated thyroid hormone levels in the blood. hCG is a hormone produced by the placenta that is identical to TSH and stimulates the thyroid gland to create more thyroid hormones. Thyroid-binding globulin, also known as thyroxine-binding globulin, is a protein that carries thyroid hormone in the blood, and its levels rise when oestrogen levels rise. T4 and T3 are free and functioning in only 0.04 % and 0.5 % of the population, respectively. Thyroid function tests during pregnancy can be difficult to interpret due to these typical hormonal changes.

What Are the Causes of Hypothyroidism During Pregnancy?

Hashimoto’s disease is the most common cause of hypothyroidism in pregnancy, which affects three to five out of every 1,000 pregnancies. 2 Hashimoto’s illness is a type of thyroid inflammation that lasts for years. Hashimoto’s disease is an autoimmune disease that affects the body’s immune system. The immune system attacks the thyroid in Hashimoto’s disease, causing inflammation and interfering with the thyroid’s capacity to generate thyroid hormones. Hypothyroidism during pregnancy can also be caused by untreated hypothyroidism or thyroid damage or removal as a treatment for hyperthyroidism.

What Are the Symptoms of Hypothyroidism?

Hypothyroidism is a fairly common disorder. If the symptoms are minor, they may go unnoticed. Hypothyroidism is a condition in which the thyroid gland is underactive and produces inadequate thyroid hormones. Symptoms of hypothyroidism may be mild and appear gradually. The most common symptoms of hypothyroidism are listed below:

  • Feeling tired
  • Rough voice
  • Swelling of the face
  • Unable to withstand cold temperatures
  • Constipation
  • Slow heartbeat
  • Weight gain
  • Muscle cramps
  • Hair and skin changes (loss of eyebrows or dry skin)
  • Irregular periods.
  • Carpal tunnel syndrome (tingling or pain in the hands)
  • Difficulty concentrating

Symptoms of hypothyroidism can be confused with those of other illnesses or medical conditions. For a diagnosis, always consult your healthcare provider.

How Does Hypothyroidism Affect Mother and Baby?

Hypothyroidism that is uncontrolled during pregnancy might lead to complications.

  • preeclampsia
  • miscarriage
  • stillbirth
  • congestive heart failure, rarely
  • low birth weight
  • anaemia too few red blood cells in the body, which prevents the body from receiving enough oxygen

Since thyroid hormones are necessary for the development of the brain and nervous system of the fetus, untreated hypothyroidism can damage the growth and development of the baby’s brain, especially during the first trimester.

Diagnosis of hypothyroidism during pregnancy

Symptoms of hypothyroidism are carefully examined, and TSH and T4 levels are measured. Extreme exhaustion, sensitivity to cold, muscle cramps, constipation, and problems with memory or concentration are some of the symptoms of hypothyroidism during pregnancy. Hypothyroidism is frequently indicated by high TSH values and low levels of free T4. Test results should be read with caution due to typical variations in thyroid function associated with pregnancy. The TSH test can also detect subclinical hypothyroidism, which is a mild form of hypothyroidism without symptoms. In 2 to 3% of pregnancies, subclinical hypothyroidism occurs. 2 TSH levels will be high, but free T4 levels will be normal. Treatment is needed if subclinical hypothyroidism is detected during pregnancy to ensure a healthy pregnancy.

Treatment of hypothyroidism during pregnancy

Hypothyroidism is treated with thyroxine, a synthetic thyroid hormone that is equivalent to T4 released by the thyroid gland. To maintain adequate thyroid function, women with pre-existing hypothyroidism will need to increase their dose of thyroxine before pregnancy. During pregnancy, thyroid function should be tested every 6 to 8 weeks. If the mother has hypothyroidism, synthetic thyroxine is safe and important for the health of the fetus.

Dietary supplements

Iodine is an essential mineral for a mother during pregnancy because it is used by the thyroid to generate thyroid hormones. The baby absorbs iodine from the mother’s food during pregnancy. When a woman is pregnant, she needs additional iodine, about 250 mcg per day. People with autoimmune thyroid disease, on the other hand, may be more vulnerable to the side effects of iodine. Hyperthyroidism and hypothyroidism can be caused or made worse by taking iodine drops or eating foods high in iodine, such as seaweed, beans, or kelp. In summary, women with thyroid disorders can have a successful pregnancy and protect the health of their fetus by learning about the effects of pregnancy on the thyroid, having regular thyroid tests, and taking essential medications.

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