It wouldn't be "another Hitler" we're afraid of, more like "another Columbine kid" or "another Osama", anyway.I think the 10 Commandments is referring to taking a human life only.
A mother doesn't have to either keep her child or have her child killed. She can always give him/her up for adoption. I don't know of anyone who expects a mother to keep the child.
But as a living human being exists in his/her mother's uterus, let's allow him/her to live.
Who knows what we've missed out on (as a society/human race) by all those individuals not having a chance to live to adulthood. Yes, some could have turned out to be another Hitler but maybe some could have found a cure for cancer or created masterpieces such as beautiful music, etc. But we'll never know because they weren't given a chance to live and grow.