<prompt> Pseudo hermaphroditism in a female child is most commonly due to:21-hydroxylase deficiency17-hydroxylase deficiency11-hydroxylase deficiency3-hydroxylase deficiency  <response>: a. 21-hydroxylase deficiencyRef: Nelsons 20e p 2714-2723, Ghai 8e p 526-527Classic 21-hydroxylase deficiency is the most common cause of ambiguous genitalia in a female newborn. Virilization is usually apparent at birth in females, i.e. Pseudo hermaphroditism of a female child. 