Always felt like babies were pretty much like objects in every game only difference is you were able to move carry the other ones. There just isn't much of anything to do with them, but you know they are babies. Always been the most lacking stage in games, since with aging on they usually get like two days?
It's nice that Grant mentioned babies are definitely on their list among other things that need improving. Though if anything I find them to need a upgrade visually a little.