Your nephew was traumatized because the predominant message he gets from his school, his friends, and the media is that this "fetus" thing is not a human being. He should have seen those images within the framework of his moral training by his family.
May his trauma develop into activism within his age group to educate his peers that it's a child, not a choice.
I think small children should be shielded from these graphics. Older ones should not.