One issue is the thought that when deciding on what to do with a, say, 23 weeker, we should look at the baby and see how he is doing before deciding on resuscitation. If he's active or crying, then go for it, and don't if he's not. As one commenter put it, we should look at his "will to live." It sounds nice, but there' s a problem with it: how a 23 to 24 weeker does in the delivery room has little bearing on their eventual outcome. Kids who look great might end up severely impaired and vice versa. In fact, even kids who need CPR in the delivery room don't necessarily do worse than the others.
A variant on the above is to see how the baby does in the first couple of days and stop heroic support if the baby is doing poorly. I agree that we should always be reassessing the baby's chances and discussing them with the parents, but there are a few practical problems with this. If the baby has a massive intracranial hemorrhage, then it can make it relatively easy, although still heart wrenching for the parents, to stop support. But even kids who have a normal head ultrasound at age two or three days can end up in the severely disabled group. It's just hard to predict. Also, although ethically stopping life support is equivalent to not starting it, parents don't always see it that way. It's probably easier for them to not start it than to stop it.
Another issue has to do with whether Scandinavian results can be extrapolated to America. Put another way, as one commenter did, you should see what your local results are and discuss those with the parents. Excellent points, but again things get a little sticky. The problem is that one of the factors most important in outcomes is socioeconomic status. Premies from homes of educated parents do better on intelligence testing and so on than premies from other homes, presumably because there is more stimulation offered to the child, more books read to them and so on.
So, if we're saying that groups with worse long term outcomes - a higher chance of disability - should perhaps not be resuscitated, then we're getting pretty close to saying that kids from lower socioeconomic groups are less deserving of resuscitation. And that's just a small step away from saying that poor black kids are less deserving of resuscitation, and I don't even want to get close to saying that.
Discrimination is a problem that's almost inherent when we use quality of life to guide us in our decisions to resuscitate or not. Usually it's discrimination against the handicapped that is mentioned, but I think that discrimination on a racial or socioeconomic basis can occur as well, and personally, I would really like to avoid that.