I don't think TSO ever implemented babies, but it did have cats and dogs, and the original offline sims had babies.
TSO has never had children or babies. Sims 2 has seven different life stages, infant/toddler/child/teen/young adult/adult/elder.
I don't quite get the appeal of the pregnancy simulators. I wish they would at least whisper; I find it annoying to hear "Baby shifts in Melanie's stomach" every few minutes while I'm playing Tringo or whatever.