Interested also now that I have played with babies in sims3 with the store content, I saw how much there was with babies; they play and squeal in the baby swing, and can go to sleep or else get motion sick if it's on too long too fast. You can take them out in strollers, bathr and change them on a changing table, use a baby monitor, and you can see their needs so you know what to address. Toddlers can only sit, and scoot on their rears, then they lean to crawl, and then you can teach them to walk, talk, and potty train, so in sims3 at least, babies graduate from infants who can't sit up on their own, to sitters, scooters, crawlers, then walkers.
So maybe they will emulate that? It seemed to work well.
