however, PTU is preferred in the first trimester and should be replaced by MMI after this trimester. Choanal and esophageal atresia of fetus in MMI-treated and maternal hepatotoxicity in PTU-treated pregnancies are of utmost concern. Maintaining free thyroxine concentration in the upper one-third of each trimester-specific reference interval denotes success of therapy. MMI is the mainstay of the treatment of post partum hyperthyroidism, in particular during lactation. Conclusion: Management of hyperthyroidism during pregnancy and lactation requires special considerations and should be carefully implemented to avoid any adverse effects on the mother, fetus, and neonate.