To abort or not to abort

[Mudhammam]

Fine but that doesn't answer my question. There's nothing consistent as far as I can see in the position that "a future expectation of personhood" be regarded more sacred than the present sentience of a pig or a cow.

If I understand Heywood argument it's that a fetus, Like a person under Anaesthesia, hopefully WILL achieve full sentience, whereas a pig or a cow won't ever be more than a pig or a cow.

I'm just trying to understand the justification for elevating one over the other. I think a rational argument could be made, on the basis of a creature's conscious experience, their awareness, pain perception, etc. that would place the "sanctity of life" something like this: Humans > higher-level animals (chimps, dogs, pigs, whales) > mid-level animals (lizards, rats, etc.) > lower-level animals (ants, worms, bees, etc.) > "potential creatures or persons" i.e. unborn humans > unborn animals.

That's just a loose summary of where I would probably start in terms of evaluating the value of life. One would really need to take a closer look at each species to place them in their proper order of sanctity. I just don't see how prolifers typically view it as: humans > unborn humans > everything else (or unborn humans > everything else).