I know that sims doesn't allow for Teens to wooho/get regnant (without mods that is). But I'm wondering what your thought would be of a baby doll simulator that sims teens could get in a 'home ec' class. It would be one of a couple of projects in that class. Depending on the life span of the particular game save the time the teen has it differs. Evil/mean/Technophobe sims could sabotage the doll (Technophobe sims could use instead the egg or flour bag method instead) by taking out batteries and get an automatic F.
Of course there would be those who would want it to be a "real baby" or those who miss the point of the real BTIO and believes it encourages teen pregnancy.
A Baby-Think It-Over is a doll simulator which teaches teens what its like to be a teen parent. It has keys and a carseat/stroller. Its also available in Middle-schools too. The point is that its to prevent teens doing woohoo and getting pregant. http://www.timolson.com/babythink.htm