I think there are many factors to be considered, like the percentage chance of passing some type of medical problem on and so forth. If it's a low risk, then I see no problem, but once you start getting higher, that's where I think it's selfish of the mother to have a child anyways. I was born with a "birth defect", even though mine is not genetic. It was just a fluke thing. Though if I knew that mine was genetic, I wouldn't want to put my child through what I have been through, so if there was a pretty high chance or even a 50/50 chance, I wouldn't have kids. I'm all for adopting, and think that would be a much better way to go.
Sorry about spelling errors. I just barely care anymore,
I think adults should limit themselves to just enough kids to replace themselves.