This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'Which drugs are used for prenatal therapy of congenital adrenal hyperplasia? \nSelect and explain. \nA. Hydrocoisone, B. Prednisolone, C. Fludrocoisone, D. Dexamethasone', 'role': 'user'}, {'content': 'Answer: D \nExplanation: High risk pregnancies should be staed of Dexamathasone, that readily crosses placenta, in an amount of 20 mu/kg in 2-3 divided doses. This surpasses secretion of steroids by fetal adrenals, including secretion of fetal adrenal androgens. If staed 6 weeks of gestation, it ameliorates virilization of external genitals in affected female fetus. Ref: Kligman, Behrman, Jenson, Stanton (2008), Chapter 577, "Congenital Adrenal Hyperplasia", In the book, "Nelson\'s Textbook of Pediatrics", Volume 2, 18th Edition, New Delhi, Page 2364', 'role': 'assistant'}]