Place baby related objects (such as: nappies, booties, bottle brush, rattle, teething ring, etc.) into separate brown paper bags.  Staple shut and number them on the outside.

Give all the guests pen and paper, pass the bags around and asks them to write down what they think is inside.  At the end, the bags are opened and whoever gets the most right is the winner.  The mum-to-be gets to keep the items.