Premature babies which some people call fetuses can live outside of the "host" body.
Also, the infant that has been born is also dependent upon someone for it's survival.
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Premature babies do exist. But how is that relevant to laws governing a woman's choice to abortion?
So after the child is born it depends on another for survival. How is that relevant to laws governing a woman's choice to abortion?
Until that baby is born, it is part of the mother's anatomy...part of her body. That natural consideration is a matter of practicality.
Is there more to it than that? Yes. A pregnant woman is likely aware that she carries a little person in her. But since it is her body and the little person is wholly dependent on this particular woman, I would say that the baby's interests are necessarily subordinated to that woman's interests and not vice-versa.
We are allegedly an intelligent species. One would think that a woman fully aware of what a pregnancy is would never willingly choose an abortion. But that's not the case.