The thyroid diseases hyperthyroidism and hypothyroidism are relatively common in pregnancy and important to treat. The thyroid is an organ located in the front of your neck that releases hormones that regulate your metabolism (the way your body uses energy), heart and nervous system, weight, body temperature, and many other processes in the body.
During pregnancy, if you have pre-existing hyperthyroidism or hypothyroidism, you may require more medical attention to control these conditions during pregnancy, especially in the first trimester.
Occasionally, pregnancy may cause symptoms similar to hyperthyroidism in the first trimester. If you experience palpitations, weight loss, and persistent vomiting, you should contact your physician.
Untreated thyroid diseases in pregnancy may lead to premature birth, preeclampsia (a severe increase in blood pressure), miscarriage, and low birth weight among other problems.
It is important to talk to your doctor if you have any history of hypothyroidism or hyperthyroidism so you can be monitored before, and during pregnancy and your treatment adjusted if necessary.
What are the symptoms of hypothyroidism?
Hypothyroidism is a common condition, which can go undetected if symptoms are mild. Hypothyroidism means the thyroid is underactive, producing insufficient amounts of thyroid hormones.
Symptoms of hypothyroidism may be mild and may start slowly. The following are the most common symptoms of hypothyroidism:
- Feeling tired
- Unable to stand cold temperatures
- Hoarse voice
- Swelling of the face
- Weight gain
- Skin and hair changes, including eyebrows
- Carpal tunnel syndrome (hand tingling or pain)
- Slow heart rate
- Muscle cramps
- Trouble concentrating
- Irregular menstrual periods
The symptoms of hypothyroidism may resemble other conditions or medical problems. Always consult your doctor for a diagnosis.
Causes of Thyroid Disease in Pregnancy
The most common cause of maternal hyperthyroidism during pregnancy is the autoimmune disorder Grave’s disease.
In this disorder, the body makes an antibody (a protein produced by the body when it thinks a virus or bacteria has invaded) called thyroid-stimulating immunoglobulin (TSI) that causes the thyroid to make too much thyroid hormone.
The most common cause of hypothyroidism is the autoimmune disorder known as Hashimoto’s thyroiditis. In this condition, the body mistakenly attacks the thyroid gland cells, leaving the thyroid without enough cells and enzymes to make enough thyroid hormone.
Diagnosis of Thyroid Disease in Pregnancy
Hyperthyroidism and hypothyroidism in pregnancy are diagnosed based on symptoms, physical exam, and blood tests to measure levels of thyroid-stimulating hormone (TSH) and thyroid hormones T4, and for hyperthyroidism also T3.
How does hypothyroidism affect the fetus?
During the first few months of pregnancy, the fetus relies on the mother for thyroid hormones. Thyroid hormones are important in normal brain development and growth of the fetus. Hypothyroidism in the mother can have long-lasting effects on the fetus.
How is thyroid function tested?
Screening for hypothyroidism involves a blood test that measures thyroid hormone (thyroxine, or T4) and serum TSH (thyroid-stimulating hormone) levels.
Hypothyroidism is often suspected when TSH levels are above normal and T4 levels are below normal. Always consult your doctor for a diagnosis.
Who should undergo thyroid function screening?
Routine screening for hypothyroidism during pregnancy is not recommended. A pregnant woman with symptoms of hypothyroidism, a history of hypothyroidism, or with related conditions (for example, diabetes) should be screened.
How is hypothyroidism treated during pregnancy?
Thyroid hormone replacement therapy is used to treat the mother. Dosage of thyroid hormone replacement therapy is based on the individual’s levels of thyroid hormones.
Thyroid hormone levels may change during pregnancy. And, the thyroid replacement dosing may also change. The treatment is safe and essential to both mother and fetus.
Routine screening for all newborns includes a test of thyroid hormone levels.