How do you get a sim pregnant for 3ds in Sims 3?

For triplets, There are a few different ways. One is having the mother watch the kid's channel on tv a lot and listen to the kid's station on the radio. Also, reading Children's Books and pregnancy books adds to the chance of triplets. The easiest way is to have the fertility treatment lifetime reward for both the mother and the father. Both of these work for me! I hope this helped!