would it be less bad to murder an old person, a middle aged person, a teenager, a child?
if you want to draw lines about what constitutes a human that doesn't start with a fertilised egg where are you going to allow it to be moved to
is it at the convenience of the slut who wants to get nutted in or what?
would you expect that someone should be liable for a mistake they make with a firearm that causes harm to others?
then i don't think it's really any different
i'd even say that the dude who nuts in the girl has liability in this also
making the creation of human life an arbitrary line of when you designate it to be valid beyond the actual biological life cycle is not doing real jurisprudence it's making excuses for psychologically immature and pathological people to do things that they should pay for