The Sims FreePlay Tips

Get Married / Have a baby
after completed all goals ( the last goal is to build three businesses in town), then next task is to propose to a sim, and then engagement ring is given which you can purchase using simStone (30). Once the relationship is more mature, then POP the question, and now your sims are married!

Once you have married sims, now you can purchase baby crib for $10,000 or using simStone under "nursery", and wait around 35hr to get an infant sim.