If it is illegal for a rape victim to kill the rapist after the fact, then why

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If it is illegal for a rape victim to kill the rapist after the fact, then why should it be legal for the rape victim to kill a baby that is the product of the rape? It seems to me that abortion is "vigilante justice" in a sense. This is all assuming, of course, that the unborn child is considered a living, human being. If it isn't, then why is an unborn child not then considered "evidence" to be used by a third party? I do not think an unborn child should be considered anything in between a "living human" and an "object," but please take this distinction into consideration.