Eugenics isn't indiscriminate killing like abortion is. In practice it has been more about sterilization than abortion, unless you count aborting defective fetuses.

I admire the goal of eugenics, to create a better man. Although every time man thinks he's superior to nature we tend to get a solid kick in the proverbial ass. And in practice eugenics is abhorrent. At least one person involved is chosing an abortion, eugenics doesn't allow for choice.