Rape would be one good example. If the woman cannot or does not desire to carry and birth the baby then the fetus is using her body against her will.
The baby would be just as much of a victim as the woman is. It is not right to punish the victim. It is against her will in this instance but to say that the baby is "using" the mother is just misleading and inflammatory.
I'll entertain your argument once draconian laws are passed and enforced against men who father children and refuse to play an equal part in rasing them. Until then, it's just men coercing women. If the fetus' welfare supercedes the woman's right to control her own body, then that same fetus owns the Father's right to choose as well and the Father must be required to give equally to the child in time, care, money, and support. No more of this one-sided business based on a fluke of biology. Sauce for the goose is sauce for the gander.
We are talking about the morality and ethics of killing a person. The morals and ethics of who should care for that person is irrelevant to the question of whether or not that person should be killed. After all we would not advocate killing a newborn just because it's father deserted it and it's mother did not want it. The main thrust of the issue is whether or not it is a person.
But I agree the needs of the baby outweigh both the mother's and the father's rights to determine their lifestyle choices. Parents must provide some reasonable care for their children. More on that later.
Yes, it is unfortunate. So how about we decide that when the baby can live outside the Mother's body that it becomes a person? Got a better suggestion? Bear in mind that the Father will be required to be there to provide support all along if we are going to deny the woman the "convenience" of owning her body, then it's only fair to deny the man as well.
How about we decide it is a person when it is actually a person using the best information we have and then whether we like the results or not we do what is right by all the persons who live in our society.
Mother's and father's must provide reasonable care for their children. If the mother decides to give the baby up for adoption then she can. If the father decides to give the baby up for adoption then he can. See everyone is teated fairly and the same.