Arboles, I'm sorry, I think I'm confusing the issue a bit here with my questions. I wasn't referring to babies born alive after abortions, but making a general comment about viability of pre-term babies. Just because the technology exists to keep these babies alive doesn't mean it's ethically the right thing to do, since the vast majority have profound disabilities that impact quality of life. One article says that ethicists have concluded that babies born prior to 22 or 23 weeks should be left to die.
documentary on 23-week babies: http://www.bbc.co.uk/news/health-12625253
I've always struggled with the question of where do you draw the line? It's arbitrary, as James W says. As little as 30 or 40 years ago, I remember the cut off for saving a premature baby was around 30-32 weeks. So if a baby was aborted at that age it might have been alive, but not considered viable. Now we consider viability to be 23 weeks. If we could not "save" these very premature babies, would it still be considered wrong to abort them?
I'm trying to figure how to phrase this dilemma, but can't quite get my head around the right words, so I'm not sure if my point is clear.