I can't tell: do you think it would make sense for most people to pick a particular sex for their child, which sex has an obviously superior utility; or do you just mean that to any given set of parents, they are sufficiently non-indifferent to the sex of the child that it should be worth it to them to screen?

That is, do you think the correct scenario is more like, "Gosh, everybody wants girls, we're going to have to start introducing legal sanctions or at least invent egg-egg fertilzation if we don't want to go extinct, but look at all the utility!", or like "Me and Joe want a little girl so we can name her after his mother, but Liz and Todd down the street are having a boy so they'll have one of each"?