Most common cause of ambigious genitalia in a female child is:
Placenta steroid sulfatase deficiency
Fetal aromatase deficiency
Wnt4 mutation
Congenital adrenal hyperplasia
“CAH due to 21 hydroxylase deficiency is the most frequent cause of sexual ambiguity and the M/C endocrine cause of neonatal death.”
Ambiguity of sex at birth—"Cases of ambiguity of sex detected at birth are due to adrenogenital syndrome unless proved otherwise".