Those things do not correlate.
It's not the same as a kidney donation, or blood donation. Nobody is asking you to give up or cripple part of your body, or forcibly take something from you to save someone, somewhere, that you hold no responsibility for.
I mean, you can stop there, because necessary transfusions or organ replacements after an assault or wreck or sports injury or
whatever qualifies for significant/total legal or ethical liability are a
thing. There are very much cases where direct and unquestionable responsibility exists, but we
still refuse, by and large
absolutely, to even consider medical coercion to save a life. Not even to the extent of mandating some degree of goddamn caretaking, nevermind anything approaching as strenuous, damaging, or risky as a pregnancy.
It's just something you cannot escape from -- even in cases where a direct chain of responsibility exists, and there's
no question about whether the one in need is human or not, just about every nation in the world refuses to consider coercion... except when it comes to women and pregnancy.
It can't be an issue of whether there's another human life involved, because even in cases where the burden and risk are much less (such as with simple blood donation or infusion or even simple temporary caretaking or somethin') and there's
zero question on whether the needy are human or not, there's functionally just no argument medical coercion is acceptable. It's pretty much always and only with women and their bodies.
And, like, that's not even getting into organ donation, specifically mandatory donation in the case of the deceased. Folks are less willing to coerce a
corpse than they are to coerce a woman, even when it would save the lives of people that are unquestionably human. Hell, not even for immediate relatives or actual living children, which would be an obvious extension to pregnancy if saving human lives were the actual concern.
Claiming it's an issue of something constituting human life just makes no damn sense given how we treat other situations. It's not how we interact with the issue of human life and medical ethics on any other issue I'm aware of, even where every prior or related concern is more or less the same.