Science works against viability being a border.
Premies from earlyer and earlyer are being rescued.
What diffrence does viability really make anyway?
If I have a disease that is likly to kill me soon how much citizenship right should I loose for being nonviable myself?
Calling them nonviable obfuscates the fact that most abortions kill perfectly healthy babies who are viable in every respect save one.
How viable is a newborn? Few creatures are as dependant as a human child.
I would certainly allow that a life threatening pregnancy , like an etopic pregnancy, should be aborted. Other than that, viability is a very arbitrary standard.