? Latin Birth Registration

[Maiden Stone]

The sin of fornication was when a single woman gave birth to a child.
If a married woman, and not her husband's child, then the sin was adultery.

Generally speaking, fornication is between 2 single people. Adultery is when either or both are married  to someone else. The sin is fornication not the birth.
Bible translations differ.

1987 General Synod of the Church of England: "....  fornication and adultery are sins against this ideal ...".

Catholic Dictionary definition
https://www.catholicculture.org/culture/library/dictionary/index.cfm?id=33619

[Tickettyboo]

As it was fornication and not adultery, the father of the baby was free to marry the mother. If he was still around and a member of the flock, he might be persuaded to "do the right thing" and marry.       

Or, more to the point for the parish purse, if  he was deemed to be the father, be made to pay for the upkeep of the child so the burden did not fall upon the parish.

Boo