Abortion in circumstances where the pregnancy was either involuntary or could pose health risks should not be questioned IMO.
On the other end of the issue, it is going to sound terrible and there is absolutely no other way to phrase it, but if a child is going to be unable to experience the world due to severe disability that is known before birth, I find a larger ethical dilemma in bringing into the world a child that is only living in the literal sense than in termination of pregnancy.