That's true, there are sudden changes in our collective evaluation of what rights a human has. There are some really plausible reasons for birth, for example,

That's true, there are sudden changes in our collective evaluation of what rights a human has. There are some really plausible reasons for birth, for example, as an important turning point: - Before (and in particular during) birth, a child's life and physical well-being is immediately tied to the mother's. There is a real risk of one's sickness killing the other. - Before birth, there is no mandatory, conscious care-taking. The embryo is automatically taken care for. Afterwards, it requires a (excuse my wording as a parent) shit-ton of work to keep a kid alive, happy and successful (however you define that) - The risk of death is vastly higher for an embryo than for a child (with about 1/3 of pregnancies being unsuccessful) and decreases strongly after birth. I suspect this is one of the reasons why abortion is often intuitively seen as different from euthanasia. That said, I completely agree with your argument that it's wrong to argue as if there was a sudden point at which humans are suddenly and naturally protected but aren't before. But I think that not many advocates would argue for such a radical position.