In the case of a biracial child, that would be more difficult - but a "devout" Catholic family would go the adoption route, not the abortion one.
We don't know if her parents even knew about the child. She may have not even told them- many families would have disowned a child for even getting pregnant by a man of a different race, no matter the outcome of the pregnancy.
Look, I am not trying to justify what she did- she should have fought for her child's life, even if she just gave birth and abandoned the child in the hospital. But the circumstances she is describing seem possible to me.
I am not hung up on "devout"- people like Ted Kennedy and John Kerry consider themselves to be devout.