The fetus does not have a thyroid gland and therefore does not produce its own thyroid hormone during most of the first trimester. At this time, the fetus derives all of its necessary thyroid hormone from the mother. For this reason, it is especially important that in the first trimester, the mother’s hypothyroidism is treated. It is, however essential to treat hypothyroidism not only during the first trimester but throughout the pregnancy. Even mild hypothyroidism can cause adverse gestational outcomes, such as preterm delivery, low birth weight, fetal death, and impaired intellectual development of the baby. (7)