Do you age up your babies or let them age naturally?

I kind of go between both, honestly. I don't hate the baby stage as much as everyone else seems to, but I admit it does get tiring after a while. I like my Sims to bond with the baby before it ages up into a toddler, but when I get the birthday notification I usually will age them up. But sometimes I just forget to. The baby stage is so short anyway.