Patient Guide to Detecting and Treating Hypothyroidism Before, During, and After Pregnancy

Pregnancy causes major changes in the levels of hormones made by the thyroid gland, located in the front of the neck. For that reason, thyroid problems sometimes can start or get worse during pregnancy or after childbirth.

The thyroid makes the hormones T3 and T4, which control metabolism—how your body uses and stores energy. When the thyroid does not make enough thyroid hormone, doctors call this underactive thyroid or hypothyroidism. 

Hypothyroidism during pregnancy is not common. However, the symptoms can be overlooked because some mimic the hormonal changes of a normal pregnancy, such as tiredness and weight gain.  If left untreated, maternal hypothyroidism poses a risk for both mother and baby. A pregnant woman’s thyroid hormones are vital not only for her but also for the development of her baby. Pregnant women with uncontrolled hypothyroidism can get high blood pressure, anemia (low red blood cell count), and muscle pain and weakness. There is also an increased risk of miscarriage, premature birth (before 37 weeks of pregnancy), or even stillbirth.

This guide for patients comes from The Endocrine Society’s 2012 practice guidelines for physicians about the detection and treatment of thyroid dysfunction in pregnancy and after birth.

What causes maternal hypothyroidism?

A common cause of underactive thyroid in pregnant women is Hashimoto’s disease, sometimes called Hashimoto’s thyroiditis. This autoimmune disease occurs when your immune system forms antibodies (immune proteins) that attack the thyroid. This, in turn, causes the gland to make too little thyroid hormone. People with this disease may have symptoms of hypothyroidism, or they may notice no effects. Other causes of hypothyroidism include prior treatment for hyperthyroidism (when the thyroid makes too much thyroid hormone) and surgery to remove thyroid tumors. The thyroid also can become underactive after childbirth. About 7% of women get  postpartum thyroiditis (inflammation of the thyroid) in the first year after giving birth. This problem starts with hyperthyroidism, which most often clears up without treatment in a few weeks or months. But sometimes the inflammation leads to hypothyroidism. In most cases, the hypothyroidism goes away on its own. In countries where there is not enough iodine in the diet, iodine deficiency is a chief cause of hypothyroidism. The thyroid gland needs iodine to make thyroid hormones. In the United States, iodine is not lacking in the diet because of the use of iodized salt. However, women who are pregnant or breast feeding need more iodine than usual and should increase their intake of this important mineral.

What are the symptoms of hypothyroidism?
 
Symptoms of hypothyroidism may include
• Tiredness
• Depression
• Weight gain
• Feeling cold
• Dry skin and hair

Hypothyroidism Risk Factors

Women are at increased risk of an underactive thyroid during or after pregnancy if they are over age 30 or have
• Past infertility or preterm delivery
• A family history of thyroid or autoimmune disease
• Type 1 diabetes or other autoimmune disease
• Prior radiation treatment of the head or neck
• Past thyroid surgery
• Thyroid antibodies, mainly thyroid peroxidase (TPO antibodies, which are often present in Hashimoto’s disease)
• A goiter (swelling of the thyroid gland)
• Current treatment with levothyroxine, a thyroid hormone
drug, unless the dose is adjusted before or soon after
conception.



Derived from The Endocrine Society