Look over at the “Was premarital sex common?” thread. The fact is that premarital sex in Ye Olden Times was very likely to lead to pregnancy. This is tolerable if the couple schtupping are candidates for marriage. Read Deuteronomy, where if a man has sex with a woman is required by Biblical Law to marry her if she (that is, her family) demanded it. “You broke it, you bought it”.
Premarital sex of this kind doesn’t threaten the social order, it reinforces it. The kids might sneak out and have sex, but before you know it they’re going to find themselves “in trouble” and they’ll find themselves married with 2.5 kids and a mortage asking themselves “How did I get here?” Same as it ever was.
But the prostitute can’t demand that her customers marry her if she becomes pregnant, assuming disease hasn’t rendered her infertile And so when she becomes pregnant she has only a few options…abortion, infanticide/exposure, or single parenting in a society where single parenting is essentially impossible. She cannot marry, because no family would allow their son to marry a woman who isn’t likely to carry the husband’s children. So the prostitute has no family, no social status. In patrilineal social systems her children have no family, they are outcasts. So her only possible social status is one outside of marriage…like a temple prostitute.