This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Management and Long-Term Consequences, Subject name: Gynaecology & Obstetrics
[{'content': 'DOC for hyperthyroidism in pregnancy: \nSelect and explain. \nA. Propylthiouracil, B. Methimazole, C. I-131, D. Thyroxine', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. (a) PropylthiouracilRef DC Dutta 7th ed./ 287; Harrison's 19th ed./ 2297* For the hyperthyroidism during pregnancy the mainstay of treatment in 1st trimester is PTU or methimazole.* Methimazole is preferable avoided during first trimester of pregnancy if PTU is available.* Methimazole and carbimazole is avoided due to fetal aplasia cutis and other defects such as choanal atresia.* Because of its rare association with hepatotoxicity, propylthiouracil should be limited to the first trimester and then maternal therapy should be converted to methimazole (or carbimazole).", 'role': 'assistant'}]