A cute idea for a centerpiece that can later serve as a toy for the baby is a stuffed animal. Get a large teddy bear, or any other stuffed animal you think the mom to be would like. Place him in a basket covered with a soft baby blanket and give him a baby bottle, a bib and hang a binkie around his neck (not to do this with a baby, of course, but for a teddy bear it's obviously ok...). You can also put a cute baby hat on his head and dress him up in a baby onsie.
Place the basket with the teddy bear in the middle of the main table and decorate it like a baby's room. You can put a music box, a cute pair of baby shoes and a mobile all around the basket, for example.
This will look really cute and all the items that are on the bear or displayed with him can be given to the mom- to-be for her new baby as well.
The bear centerpiece can also serve as your gift to the new mom, so you can even stuff the basket around the bear with a bunch of baby items (socks, bibs, onsies, wipes, toys, pacifiers, etc...). Or if you prefer to just have the bear in the basket by himself, you can put the extra baby items all wrapped in pretty paper around the bear basket.
