Heard that you need to be level ten to get sims married and have children?
Well it ain't true! You can be any level you like. Here's the cheat for it anyway:

1. Make two sims be romantic to each other until their relationship bar says partner, make them do woohoo twice
2. Buy the ring that cost 10LP and make sure the two sims relationship bar to each other is now engaged
3. Fill up that relationship bar to married by making them woohoo
4. Buy the pink crib that cost 16LP and place it in the married couples home
5. Tap the icon above the crib
6. Pay 3LP to buy the baby
7. Wait 24Hours to get the baby
8. Choose the baby's name, gender, eyes and outfit
9. Make one parent be rude to the other
10. Make the couple divorce
11. Enjoy a single parented household
12. You can make the parent be friends with the baby by using the cuddle thing
13. Voila, it only works if the couple stay divorced but they also live in the same house.