Hyperthyroidism in pregnancy leads to a lot of complication in mother as well as in foetus..Hyperthyroidism in women who are of childbearing age is predominantly of autoimmune origin and caused by Graves’ disease.Graves’ hyperthyroidism affects 0.2% of pregnant women.The physiological changes in the maternal immune system during a pregnancy may influence the development of this and other autoimmune diseases. Furthermore, pregnancy–associated physiological changes influence the synthesis and metabolism of thyroid hormones and challenge the interpretation of thyroid function tests in pregnancy. Thyroid hormones are crucial regulators of early development and play an important role in the maintenance of a normal pregnancy and in the development of the fetus, particularly the fetal brain. Untreated or inadequately treated hyperthyroidism is associated with pregnancy complications and may even program the fetus to long–term development of disease. Pregnant women with hyperthyroidism need careful management as some may be at increased risk of fetal loss, pre–eclampsia,heart failure, premature labour, and having a low birthweight baby. Hyperthyroidism in pregnant women should be carefully managed and controlled, and proper management involves different medical specialties. The treatment of choice in pregnancy is antithyroid drugs (ATDs).