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Guidelines for Thyroid Disease & Pregnancy

American Thyroid Association Issues Guidelines for Pregnant Women


Updated January 28, 2009

Guidelines for Thyroid Disease & Pregnancy

The American Thyroid Association has advice regarding hypothyroidism and pregnancy

In 2004, the American Thyroid Association issued a public health statement regarding hypothyroidism and pregnancy.

Endocrinologists have agreed for decades that overt hypothyroidism needs to be treated during pregnancy to prevent an adverse outcome for both mother and baby.

What is controversial, however, is the the need for frequent testing during pregnancy, the likelihood of a need for increased thyroid hormone medication during pregnancy, and the risk of thyroid antibodies -- among other factors. Many physicians have differing opinions on these issues.

The American Thyroid Association (ATA) statement claimed that there is a potential for an adverse outcome when a mother has subclinical hypothyroidism -- where the T4 levels are normal, and TSH is slightly elevated -- and when a mother has thyroid autoantibodies indicative of autoimmune thyroid disease.

The bottom line? The ATA is now saying that even mild hypothyroidism can cause serious problems with the pregnancy, including premature birth or lower IQ in the baby.

This was a major departure, as until these guidelines were issued, recently, many endocrinologists insisted that thyroid antibodies and mild hypothyroidism had no impact on fertility, pregnancy, or the development of the baby.

According to the ATA Statement:

- Pregnant mothers with overt or subclinical hypothyroidism are at an increased risk for premature delivery.

- Pregnant mothers with detectable thyroid autoantibodies and normal thyroid function are at an increased risk for miscarriage and for postpartum thyroid disease including thyroiditis, hyperthyroidism (Graves’ Disease) and also hypothyroidism.

- The offspring of mothers with thyroid hormone deficiency or thyroid stimulating hormone elevation during pregnancy may be at risk of mild impairment in their intellectual function and motor skills.

- Pregnant women being treated with thyroid hormone replacement often require a 30-50% increase in their thyroid hormone dose.
The ATA called for more extensive research into the nature of these problems, as well as the need for expanded testing programs.

In the meantime, routine TSH screening is recommended for all women as a standard part of their first full OB visit. The ATA also called for testing before pregnancy and in early pregnancy of women who are at high risk for thyroid disease. Those at risk include those who have had previous thyroid problems, those with previous or existing autoimmune disease, and those with thyroid and autoimmune conditions in the family.

And, among those women who are already diagnosed with hypothyroidism, experts recommend more frequent testing during pregnancy to ensure that they are not subclinically hypothyroid, and to ensure a proper dosage is maintained.

What Should You Do?

While the ATA and endocrinologists debate which research is necessary in the bigger picture, women who are contemplating pregnancy have options to consider:

Women who are contemplating pregnancy -- even those without a personal or family history of thyroid or autoimmune disease -- should, as a precautionary measure, get a basic TSH test. This can be done through your doctor, or in many states, you can order your own tests.

Any woman who has a personal or family history of thyroid or autoimmune disease -- should have her thyroid tested prior to becoming pregnant, and again within the first weeks of early pregnancy. She should be tested throughout the pregnant as often as symptoms might indicate, but at least once a trimester.

Any woman with a diagnosed thyroid condition should have her thyroid tested prior to becoming pregnant, and again within the first several weeks of early pregnancy. She should be tested frequently throughout the pregnancy, including several times in the first trimester, and throughout the pregnancy as often as clinical signs and symptoms might indicate, but at least once in each of the second and third trimesters.

Women contemplating pregnancy should make sure they start taking a prenatal vitamin that includes not only folic acid, but iodine, before becoming pregnant, and continue taking that vitamin throughout pregnancy. (Note, however, that women taking a prenatal vitamin with iron will need to be careful about separating the vitamins from their thyroid hormone by at least 3-4 hours at minimum, or the iron may make the thyroid hormone less effective by interfering with absorption.)

Find out more information about the ATA Statement.


ATA Public Health Statement, "American Thyroid Association (ATA) Statement on Early Maternal Thyroidal Insufficiency: Recognition, Clinical Management and Research Directions," April 26, 2004, Online

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