Treating mildly low thyroid function during pregnancy might not be worth the trouble, according to a new study.

Pregnant women need enough iodine for their baby's brain to develop well. But too much iodine can backfire by interrupting normal hormone production.

In the midst of all the tests and check-ups that women undergo during their pregnancies, women may want to ensure that their thyroid is tested early in pregnancy, or even before they become pregnant.

More pregnant women may have low thyroid levels than doctors currently realize - over five times more than the currently accepted rate of two to three percent.