Should You Test for an Underactive Thyroid?
It’s been linked to miscarriage, preterm birth and developmental delays. Why aren’t more OBs screening expectant moms?
The controversy over universal testing
Because of the potentially devastating consequences of too-little thyroid hormone in pregnancy, the ATA recently suggested that all pregnant women older than 30 (the risk of hypothyroidism increases with age) receive thyroid screening as well as those with a history of miscarriage, preterm delivery or infertility. But depending on the study, testing only “at-risk” women misses 30 percent to 80 percent of women with thyroid problems.
Testing everyone is problematic, too, because research is mixed over whether treating women with milder cases of hypothyroidism is beneficial or a waste of time and money.
To complicate facts further, a recent study in the New England Journal of Medicine tested the IQs in 3-year-olds and found no difference among those whose mothers had hypothyroidism—mild or severe—and took medication and those who had the condition but were not treated. However, the treatment, begun mostly after the first trimester, may have come too late to be effective.
Multiple large studies are under way to test the potential harms of mild and severe hypothyroidism in pregnancy and whether thyroid medication helps, but results aren’t due for several years. “Thyroid function in pregnancy is a very rapidly evolving field,” says Stagnaro-Green of the ATA. “A woman should discuss it with her OB or internist. Our guidelines were developed to optimize the health of the mother during pregnancy and the healthy development of the fetus.”