@we dont knwo what motivated her"

Well perhaps it was beacuse she is 17 this was a totally unplanned and unwanted baby and that she just gave birth to it on the floor and probably feared it might not be normal and healthy.
What the fuck do you expect her to do. She was obviously not getting enough moral support over this, and she went into blind panic at the prospect of having to look after this baby for life.
Its not her fault, and she does not deserve life in prison.