babies

you can actually have a baby just by being really close and doing lotsa woo's or kisses, sometimes it takes a while but eventually you'll be asked if you want to have a baby... just keep at it!

As other people have said, choose the "Try for Baby" option. If your Sims don't live together, the "Try for Baby" action won't appear unless you're on the female Sim's lot (female Sims can only get pregnant when they're player controlled) If you're feeling impatient, use a hot tub. Your Sims won't go to sleep afterwards, and you can have them keep trying until you hear the lullaby music.

well, you need to pick "try for baby".. try a few times and you'll listen a nursery song music.. and the woman sims will run to toilet to vomit after sometimes..