Look at it this way, bullcat, many children who could have relatively happy lives are aborted just because they have something like Down's, or will have dwarfism (big freaking deal, so they'll be short, that's no excuse to murder them). Other babies are murdered because they are conjoined twins. Even if they can't be separated many such twins have lived fairly full lives, with jobs and friends. There were mothers who had abortions because their babies would be born with phocomelia (short arms and/or legs) because they had taken thalidomide while pregnant. Many people with this disorder have gone on to live full lives, even if they do need assistance. I think that the correct thing to do is allow a child to be born and then care for them the best you can. Being disabled doesn't make you less of a human being.
Some conditions are on the border line, like anencephaly or thanatophoric dysplasia, the conditions that are deemed "not compatible with life" in which the baby will die anyway shortly after birth. Even in this case I would choose to let the child be born, live a few days or hours with only comfort care, whatever G-d decides is right, not me or the doctors.