PS Here is what it says on deaderpool's site:
"The MC Pregnancy module contains functionality specifically oriented to enabling other Sim households within the neighborhoods to have children and get married.
The random pregnancy/marriage checks run at midnight. They run on different days depending on the game speed. The faster the game, the more often they run to allow more pregnancy/marriage chances before the Sims get too old to have children or get married. If a game is on No Aging, the check runs once a week and Sims will have a totally random chance to have the children and get married instead of it being based on the amount of time they have until age-up."