Pediatrics The most common cause of ambiguous genitalia in a newborn is: A 21 hydroxylase deficiency B 11b -hydroxylase deficiency C 17a -hydroxy alse deficiency D 3 b-hydroxysteroid deficiency 💡 Explanation The most common cause of ambiguous genitalia in a newborn is: ✓ Correct Answer: A. 21 hydroxylase deficiency