Prenatal Testing of Thyroid Debated

Article Courtesy of The New York Times

When women think about pregnancy, the thyroid gland is seldom the first thing that leaps to mind. Nestled in the neck, the gland makes hormones that govern metabolism, helping to regulate body weight, heart rate and a host of other factors.

But if the thyroid malfunctions, it can produce too little or too much of these hormones. During pregnancy those conditions, known as hypothyroidism and hyperthyroidism, respectively, may lead to miscarriage, premature birth and pre-eclampsia — and in the case of hypothyroidism, impaired intelligence in the child.

A decade and a half of research has now brought the cumulative evidence of these risks to a critical mass. Clinical guidelines call for vigilant monitoring and treatment of patients to keep thyroid reserves normal and to safely guide women through pregnancy and early motherhood.

But because thyroid problems can easily go undiagnosed, the hazards have also set off a debate over whether every woman who is pregnant or planning to be should have a blood test to check her thyroid. That test measures for thyroid-stimulating hormone, or T.S.H., which spurs the gland’s hormone production.

Most doctors’ groups have not endorsed universal prenatal thyroid screening, citing uncertainties over whether it would yield health benefits justifying the expense of testing in roughly 6.4 million pregnancies each year and educating doctors to read results that are tricky to interpret.

But the big unanswered question — and crux of the debate — is whether treatment would help women with a mild, common form of thyroid deficiency, called subclinical hypothyroidism. For now, medical societies advise testing only high-risk women.

As a matter of policy, Dr. Kenneth D. Burman, the president of the American Thyroid Association, agrees with that stance for now. Yet like more and more endocrinologists, he offers T.S.H. pregnancy testing in his practice, at Washington Hospital Center in Washington.

“Every patient I see who’s considering getting pregnant or is pregnant gets a thyroid function test,” he said. “And I think that’s the right thing to do.”