Nothing about the right to life has ever been brought before the USSC in a way that forces the issue and requires a decision about when life becomes protectable.
Should it ever happen I hope it does while a conservative majority sits in judgement.
Regardless, it is a civil right. You can’t just walk up to a person to say “Your mother doesn’t want you” and kill them. Slavery was an obvious moral wrong before it was outlawed. We merely justified it by claiming slaves weren’t fully human.
This is less of a legal issue and more of a moral one.