This cheat works on catz and dogz, basicly all you do is get your petz to fall in love, make sure they're adults. then when it says Kittens/Puppies are due in a few days close the programme go down to your clock (on the comp) click on 'adjust date/time' then set the time foward about 5 days and then load the programme back up click on your pregnant pet then they should be in the nursery.
Don't change the time:
Changing the time on your dog 5 game or catz 5 will cause your game to freeze after a few days evenn if you only do it once! The only way to get your game working after that is to uninstall it and loose everything you've earned!