So, if someone can decide to not give a nail clipping to save 100 people, why shouldn't a woman be allowed to not give a whole plethora of bodily resources to sustain a life for months in the womb? I think this is the logic it relies upon.

I dont think that is a valid analogy. Abortion is not to deprive the foetus of resources, abortion is a physical assault on the foetus that actively and deliberately kills it. Also there is the fact of criminal negligence which is to allow harm to happen to someone else either by action or inaction when a person ignores a known or obvious risk, or disregards the life and safety of others.