Hyperthyroidism in pregnancy should be managed cautiously, but management is necessary. Anti-thyroid drugs such as Methimazole and Carbimazole are teratogenic and must be avoided in pregnancy especially in the 1st trimester. So in pregnancy, the drug of choice for hyperthyroidism is
Propylthiouracil (PTU)
But Propylthiouracil is potentially hepatotoxic. So closely monitor the liver function tests and stop this drug if signs or lab evidence of hepatotoxicity appears.
Remember to stop antithyroid drugs in the last month of pregnancy to avoid suppression of fetal thyroid hormone production. Check the thyroid profile of the new-born as soon as possible and start replacement as soon as possible if there is hypothyroidism.
