[Miharu]

Usually the shower is coordinated by someone like the mother-to-be's mother or sister, or a close friend.

I believe this person will usually inquire as to the gifts the mother-to-be wants in order to do registries. Naturally, this person can also ask about belly size and such, although there is also obviously the possibility of games that don't require such information.

I know times are changing, and this kind of thing doesn't matter so much anymore, but that's the traditional way.