Not so. You're looking at it from the wrong standpoint. Libertarianism only requires that result if you do not acknowledge the humanity of the unborn child. Libertarianism can be framed in terms of legitimate state use of force -- the state only legitimately uses force to protect its members from force and violence by others. Thus, a state may, and probably must, enact laws prohibiting murder, assault, rape, etc. This is the minimal basis of any society, and only anarchists would argue that a state has no legitimate right to act to prevent the murder of defenseless members.
If the unborn child is a human being, that defenseless human being is entitled to protection by the state since it is incapable of protecting itself from violence by others.
True, but you do not at all address the problem that is rape: it's insult added on injury to be legally bound to bear your rapist's child.
That's why I said the waters were murky in such a case.
IMHO, you put too much faith in the state.
I can appreciate the sentiment, but the fact is that once you give the state such authority, they can exercise it at their pleasure. Imagine gun control laws ostensibly passed to protect children in a home, and then extended under this doctrine to cover any home where a pregnant female could conceivalbly reside.
If you think that sounds ludicrous, take a look at what passes for "having a substantial effect on interstate commerce".