On the one hand, Pariah's right.
On the other, there are in fact places in the world where this would indeed be considered a porn site and legally prosecutable -- parts of the Islamic world, for instance.
And there's nothing to keep some nutball prosecutor, even in the United States, from hauling you into court for a nude Millenium Kid, even if there were no sexual context whatever. People have been prosecuted for taking snapshots of their own kids in the tub -- the sort of snapshots our granparents took all the time. People are rarely convicted in such ridiculous cases, but I'm not sure they're never convicted -- and in any case, the expense and public humiliation is ruinous.