Thyroid Disease During Pregnancy
Managing thyroid diseases during pregnancy is important for healthy growth of the fetus. Pregnancy can also trigger thyroid disorders.
In hypothyroidism, the thyroid is underactive and does not create enough hormone. Because a developing fetus does not make its own thyroid hormone until about 20 weeks, it depends on the mother’s thyroid hormone during the first half of pregnancy.
Research has shown that women with hypothyroidism who are not adequately treated during pregnancy may have children who score lower on IQ tests at ages 5-6.
Women at risk for developing thyroid disease include those with a goiter (an abnormally enlarged thyroid gland) or a strong family history of thyroid disease. They are screened before or early in pregnancy for hypothyroidism. Symptoms of hypothyroidism include fatigue, dry skin, constipation, intolerance to cold and mood changes.
Women with hypothyroidism need careful monitoring with TSH blood tests before and during pregnancy. For a pregnant woman with preexisting hypothyroidism, her dose of thyroid medication may need to be increased by 30 percent to 50 percent during the first trimester of pregnancy to keep it as close to normal as possible.
An overactive thyroid gland in hyperthyroidism produces too much thyroid hormone. Hyperthyroidism can significantly accelerate the body’s metabolism, causing sudden weight loss, a rapid or irregular heartbeat, sweating and anxious feelings. Hyperthyroidism that occurs during pregnancy can be harmful to the mother and baby.
Women who have symptoms are screened with a blood test. When hyperthyroidism is diagnosed, it can be treated with medication that blocks the production of thyroid hormone. The medication dose is adjusted throughout pregnancy.
Inflammation of the thyroid gland, called postpartum thyroiditis, is a common problem that occurs one to two months after giving birth in women who are predisposed to developing autoimmune thyroid disease. This may occur as either an overactive or underactive thyroid. Since symptoms are often attributed to being postpartum and the stress of having a new baby, a diagnosis of postpartum thyroiditis is often missed.
Postpartum thyroiditis is usually a self-limited condition which resolves within a few weeks to months. Treatment may be needed temporarily, based on symptoms.