I wasn't looking at it under the category of sin, but in the separation of the mother and child; and in that aspect, it's just as lamentable either way. A society shouldn't encourage women to hide their illegitimate children in orphanages out of shame. That would also be intrinsically sinful.
I don't think it is sinful to have a sense of shame over having an illegitimate child. The child is a result and symbol of committing a sinful act. How would a person who understood this not feel shame?
In my experience, women who are mainly interested in hiding their sin have abortions. Women who give up the child tend to be acting in what they believe is in the best interest of the child. Given all the problems associated with being raised by a single mother, it is a reasonable belief.
From what I have seen, women who keep the child tend to have a poor grasp of the sinfulness of fornication and do not feel much shame about getting pregnant. I do not see how it is intrinsically a more moral choice than giving up the child. In some situations, keeping the child could be irresponsible and selfish.
There are two sins I'm referring to here: one on the part of the people who would encourage the mother to abandon her child out of shame, and the other on the part of the mother herself who abandons her child. In some cases the pressure on the mother might have been so extreme that she would hardly have been at fault at all.
Yes, in some cases, it might be best for the mother to give up her child; but to enforce this with shame, rather than permitting it only when necessary, is a corruption of morals/standards. The child is not merely a symbol of shame or sin, and should not be punished for her mother's sin of fornication.
The fact is that in these societies a woman brave enough to keep her illegitimate child would be forced to bare the shame of it for the rest of her life, whereas the woman who would fornicate with dozens of men but who had the "prudence" to use some kind of contraception or even abortion would later be able to get married and take part in "polite" society without issue. This is a corruption of morals/standards. It has nothing to do with the gospel and everything to do with worldly standards of respectability and familial pride. Children should not be separated from their mothers without grave reason, and the loss of honour is not sufficiently grave. Could we justify it to a child who grow up in an orphanage by saying, "sorry, but you're a symbol of sin and fornication, and your presence would have damaged the family's honour"?
From what I have seen, women who keep the child tend to have a poor grasp of the sinfulness of fornication and do not feel much shame about getting pregnant.
There's no shame in getting pregnant. If one woman commits fornication once and gets pregnant, and another commits it ten times but does not get pregnant – which has the greater shame? How does getting pregnant add to the sin of fornication? If anything, it would partially take away the shame, because at least something good has come out of the evil, nature has been allowed to take its course, and the parents can repair for their sin by raising the child.