Assessment of thyroid disease in pregnancy is important for gestational maternal health, obstetric outcome and, subsequent development of child. Pregnancy has profound effects on the regulation of thyroid function, and on thyroidal functional disorders, that need to be recognized, carefully evaluated and correctly managed. In women with normal thyroid function there is an increase in thyroxine (T4) and triiodothyronine (T3) production and inhibition of thyroid-stimulating hormone (TSH) in the first trimester of pregnancy,. In the pregnant woman, elevated thyroxine-binding globulin (TGB) and concomitant increases in total T4 and T3 levels plateau at 12-14 weeks of pregnancy, and free T4 measurements slowly decrease. The most frequent thyroid disorder in pregnancy is maternal hypothyroidism. It is associated with fetal loss, placental abruptions, preeclampsia, preterm delivery and reduced intellectual function in the offspring. Hyperthyroidism during pregnancy is relatively uncommon, with a prevalence estimated to range between 0.1% and 1%. The most common cause of hyperthyroidism is Graves disease, as this etiology accounts for 85% of clinical hyperthyroidism in pregnancy. Another cause of hyperthyroidism is hyperemesis gravidarum. This is common and requires differentiation from Graves disease. There has been much discussion and many publications on the optimal management of pregnant women who are hyperthyroid or hypothyroid. Despite the lack of consensus organizations, which are based on analyses, support screening in all pregnant women in the first trimester for thyroid disease. In this article, we provide information about the current approaches of thyroid dysfunction in pregnancy.