Fetus doesn't even have brain activity until it's about 6 weeks old. Thus, aborting a fetus which is 6 weeks or younger strikes me as 100% ethical, since it's also never had any prior brain activity. Since I think of intelligence as the hallmark of what makes humans valuable, abort that 6 week or younger fetus. I'm still okay with abortion which occurs later than 6 weeks, though I think it gets increasingly ambiguous, and I would possibly be okay with disallowing third trimester abortions except in cases of medical emergency, since there's been several months for the mother to make a decision at that point.