You can take a theoretical pro-choice position to its logical conclusion, abortion until birth by choice. You could even go one step further and be pro-infanticide. The neonate is totally dependent upon its mother and it is hard to get rid of a baby at short notice.
You could also, at an equally ridiculous level ban all abortion for babies conceived from consensenual sex as, after all, pregnancy is always a risk from sex and why should society pay the cost of abortions.
The reality is that reduction ad absurdum arguments rarely produce good decisions on nuanced and ethical issues.
So society makes messy compromises for difficult situations, in our case abortion to 24 weeks. The vast majority of the populace favour this limit or slightly lower, with the extremes on both sides.
There is very little movement of public opinion (even just including females) on this issue so it becomes a sterile discussion rehashed every few months on MN (and I am sure on similar sites).