What if the children sacrificed are the ones who would expected to quickly die anyway? Young cancer patients, for instance, or any chld born with a defect that would have led to a very early death without modern medical care.

Their suffering would be diminished since it wouldn't last as long, and as a dark "plus", their parents were already facing the prospect of the child dying young.

I didn't see the show so I don't know if there was a caveat saying they had to be healthy children. Incidentally did the aliens describe the fate worse than death at all? Is it torture, or more like Borg-assimilation?