There is no justification for a healthy woman to abort a healthy foetus "at any stage of pregnancy." This is a completely unreasonable position to take. Have you ever been in an operating theatre and seen a breathing, fully-formed and probably-viable baby be removed from a woman's body? I have. I watched the baby die, too.
The time limit for abortion has been reduced over the years. It used to be 28 weeks in the UK - now it's 24 weeks, because many babies are able to survive and thrive at 28 weeks of gestation, due to advances in neonatal care.
I think it's exceptional, but aren't there cases where women don't realize they are pregnant until they are already a few months into their pregnancy? Like, I think I've read about cases where someone continued to get her period whilst being pregnant, stuff like that. Since the viability of a foetus will continue to be earlier and earlier due to advanced technology, this could lead to (once again, likely exceptional) situations where a woman finds out she's pregnant but can't abort anymore.
The uniqueness of each case is what makes it so hard to codify something like abortion imo, because laws are usually pretty black or white, while this topic is anything but. As a man I don't want to impose anything whatsoever about what women should do with their own bodies. However, people who go on about "so we should just let a heavily pregnant woman go to the hospital for an abortion" are talking besides the point imo. If you want an abortion you'd have done it way earlier, I can't imagine a scenario where a mother-to-be carries a baby for up to 8 months, builds an emotional connection with it, then decides to have an abortion after that. Of course there are scenarios where the health of the mother is in jeopardy but like you say, that can/will be solved by giving birth rather than abortion.