The only thing that matters is capacity to survive outside of the womb, since this differentiates the outcome of the choice.

One time when I was in college pro life protestors came on campus and being the foolish bleeding heart liberal I was I went to debate one of them. I inuited this idea during the conversation and they hit me with a "well, that's invalid." No explanation, no reasoning, just refutation via nuh-uh. It was so incredibly upsetting that I just walked away. Fuck that person. I'd be pro choice with no other reason besides that conversation.