Only the ignorant translate almah as virgin. See for example The New Jerome Biblical Commentary for a scholarly Christian view, or the introduction to the Zondervan Interlinear Hebrew-English Old Testament.
ML/NJ
Are you serious? Pray tell, what sign would there have been if a young woman conceived a child?
From the Blue Letter Bible online concordance:
almah
1) virgin, young woman
a) of marriageable age
b) maid or newly married
"There is no instance where it can be proved that 'almâ designates a young woman who is not a virgin. The fact of virginity is obvious in Gen 24:43 where 'almâ is used of one who was being sought as a bride for Isaac." (R. Laird Harris, et al. Theological Wordbook of the Old Testament, p. 672.)
I think it should be the other way around, "Only the ignorant translate almah as young woman.".