Well, I don't remember much about it, but there is a cheat called "boolprop testingcheatsenabled_true" which 你 can use to get the Tombstone of Life and Death, and impregnate a Sim using any Sim in the household. They are guaranteed to become pregnant. Sorry I can't be of 更多 help with this one; I haven't used boolprop because it gives my computer problems.
Or, 你 could do it the 老式 way: Having a male and female Sim be relaxing together on a 床, 床上 (or hot tub, 或者 你 can use a changing booth) and have one Sim selected, then select the other and pick "Try For Baby". If 你 hear little chimes at the end, then you're going to have a baby (or babies!) in three days!
BoolProp testingCheatEnabled true The Shift and Click on the mailbox, it will say "Set pregnancy relations with..." 你 click on that and then click on the name of the father 你 want.