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Hypothyroidism and Pregnancy

The thyroid is responsible for secreting several hormones into the bloodstream: thyroxine (T4), triiodothyronine (T3), reverse triiodothyronine (RT3), and calcitonin. Hypothyroidism is a condition in which the thyroid produces less hormones than it should.

Thyroid hormones are vital for the development of a foetus’s brain and nervous system. It is important that a mother has a healthy thyroid, because the foetus relies on the mother’s supply of thyroid hormones during the first and second trimesters.

Hypothyroidism can have serious consequences if one is trying to get pregnant or if one is already pregnant. If one is suffering from fertility issues or repeated miscarriages, it may prove prudent to have one’s thyroid checked by a healthcare professional.

Symptoms

The many symptoms of hypothyroidism are listed below:

  • Goitre due to thyroid enlargement
  • Fatigue
  • Weight gain
  • Sensitivity to the cold
  • Constipation
  • Loss of libido
  • Hair loss
  • Brittle hair and nails
  • Dry, itchy skin
  • Weakness
  • Muscle and joint pain
  • Depression
  • Memory problems

The symptoms listed above are numerous, but one may ask: “What are the symptoms that relate to pregnancy?” The symptoms of hypothyroidism that relate to pregnancy are as follows:

  • Fertility issues
  • Irregular periods
  • Miscarriage
  • Premature birth
  • Low birth weight
  • Problems with foetal brain development

Hypothyroidism is known to cause fertility issues. Typically, a woman releases an egg each month during ovulation. For women who suffer from hypothyroidism, ovulation occurs less often or not at all. In addition, hypothyroidism causes irregular menstrual cycles, which can add to one’s fertility issues.

If one is already pregnant, hypothyroidism can lead to miscarriage or premature birth. Babies may be born with low birth weights or problems with their mental development.

Causes

One of the most common causes of hypothyroidism in pregnancy is Hashimoto’s disease (also known as Hashimoto’s thyroiditis). Another common cause is an insufficient amount of iodine in one’s diet. Other various causes for hypothyroidism are listed below:

  • Problems with the pituitary gland
  • Infection (i.e., infections from aureus, Streptococci, or mumps virus)
  • Previous thyroid surgery
  • Medications (i.e., interferon and lithium)
  • Genetics

Risk Factors

Women are more at risk for developing hypothyroidism than men. Other risk factors for developing hypothyroidism include the following:

  • Family history – The likelihood that one will develop hypothyroidism increases if one has a family member with a thyroid condition.
  • Autoimmune disease – Individuals that have a pre-existing autoimmune disease, such as Type 1 diabetes or celiac disease, are more likely to develop another autoimmune disease, such as Hashimoto’s disease. Hashimoto’s disease is one of the leading causes of hypothyroidism.
  • History of previous thyroid problems – If one has had previous problems with their thyroid, they have a higher risk for developing additional problems. For example, thyroid cancer and its treatment can lead to hypothyroidism.

Diagnosis

A doctor may not suspect hypothyroidism solely from one’s symptoms. Many of the symptoms of hypothyroidism mimic the symptoms of pregnancy (i.e., fatigue, weight gain, and constipation).

However, a doctor may suspect hypothyroidism in pregnancy after reviewing one’s medical history and risk factors. If a doctor does suspect hypothyroidism, the following tests will be performed to confirm the diagnosis:

  • Thyroid function test – A thyroid function test is a type of blood test. It is used to check the levels of thyroxine (T4) and thyroid-stimulating hormone (TSH) in the blood. TSH is released by the pituitary gland, and as its name suggests, serves to stimulate the thyroid into producing more thyroid hormones, such as T4. Hypothyroidism is characterized by high levels of TSH and low levels of T4.
  • Thyroid antibody test – A thyroid antibody test is another type of blood test. It is used to check the levels of thyroid antibodies within the blood. Elevated levels of thyroid antibodies indicate one’s hypothyroidism is caused by an autoimmune response against the thyroid.
  • Ultrasound – A doctor may use ultrasound to view the thyroid. Ultrasound allows a doctor to measure the thyroid and check for any abnormalities. It should be noted that the thyroid is expected to grow somewhat during pregnancy. However, too much growth may signify hypothyroidism due to iodine deficiency.

Complications

If one’s hypothyroidism is not treated in pregnancy, it can lead to the following complications:

  • Preeclampsia
  • Anaemia
  • Placental abnormalities
  • Postpartum haemorrhage
  • Miscarriage
  • Premature birth
  • Low birth weight
  • Problems with foetal brain development

Treatment

The treatment for hypothyroidism involves adding a daily medication to one’s regimen. This medicine, known as levothyroxine, serves to supplement one’s own levels of thyroid hormones. Levothyroxine is safe and effective to use while pregnant.

When taking levothyroxine while pregnant, one will have to visit the doctor every four to six weeks to check on one’s thyroid hormones. The dosage of levothyroxine may have to be adjusted every so often to ensure the baby is receiving an adequate supply.

Prevention

Iodine is necessary for thyroid function. Women who plan to get pregnant, are pregnant, or are breastfeeding must maintain a diet that contains at least 250 micrograms of iodine per day. Women can achieve this by taking prenatal vitamins that contain at least 150 micrograms of iodine or at least 197 micrograms of potassium iodide.

Women who are at risk for developing hypothyroidism should have their thyroid checked at the onset of their pregnancy. It is important to start treatment for hypothyroidism as early as possible. Women previously diagnosed with hypothyroidism before pregnancy must make sure that their medication is increased to the appropriate dosage.

 
 
 

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