From The Guardian.

As you say, the genie is out of the bottle.

If physical alteration of a child is done prior to birth, does it fall under the same "part of a woman's body" category as it does in abortion controversies?

If a woman can legitimately destroy a fetus, what makes it unethical to alter one?

I don't have a hard position on this one way or another. As you say, way too many ramifications. The ability to alter the natural structure of a child will, moral or not, lead to an eventual loss of valuable biological diversity. The human race can't afford to breed itself into one genotype of any kind. A single disease could knock us off like a field of hybrid corn.