because there is nothing magical that happens to alter a viable fetus between the interior and the exterior of a birth canal in the ninth month of pregnancy.
Exactly.
The fetus is no more entitled to the use of the body of its parents than an actual child would be.
Take you: you're unquestionably human and sentient, capable of articulating a desire to live, but if the day ever came that you would die without, say, one of your mother's kidneys, or her bone marrow, or even a pint of her blood, you would not have the right to compel her to provide these things against her will.
Good heavens, enforce Roe v. Wade.
Why would a Canadian "enforce" US law?
Once the fetus becomes viable, the state has certain interests in protecting it. IOW we aren't talking only about one set of chromosomes here. It's not just the woman and her interests at stake. There is also another nacient human life.
Sure... but why should this "nacient life" be entitled to more rights than full-fledged life? As you said, there's nothing magical that happens between the interior and exterior of the birth canal.
If in the ninth month the pregnancy is killing her, then by all mean, abort! But if she is just tiring of being pregnant? are you kidding me? You could at least have suggested delivering the baby and either keeping it or placing it up for adoption.
It's worth pointing out at this point that
@BilliardsBall 's fake scenario never actually happens. Someone who's voluntarily gone through 9 months of pregnancy generally wouldn't seek an abortion unless something was horribly wrong.
@BilliardsBall was playing a game to create what he considers to be the absolute worst case he could imagine for abortion. It's a bit odd, though, since if abortion of 9-month-old fetuses was really a cause he actually cared about, it would suggest other positions that he's not taking (e.g. good availability of early-term abortion).
That being said, the reason doesn't matter to their rights... just as the reason doesn't matter when someone refuses to donate an organ or tissue. It would be pretty awful for, say, a father to refuse his bone marrow for his baby with leukemia just because he's tired of changing diapers, but we don't strap him down and take the bone marrow just because we think his reason is bad. He said no, so we respect that.
It's also worth pointing out that the pregnant person's right is to end the pregnancy. In
@BilliardsBall 's scenario of someone who somehow gets tired of being pregnant at 9 months, inducing a live birth would also end the pregnancy.
... but since I'm not interested in having a reasonable conversation with
@BilliardsBall as if I respect his position, I wasn't going to get into that level of nuance with him.