Yes, sort of. The way it works is, you save your game as she's going into labour and BEFORE the message pops up that talks about the stork arriving. If you end up with a boy and want a girl, exit the house without saving again (or it will write over your last saved spot and you'll be stuck with the boy) and re-enter. Voila, she'll be going into labour again.
Keep doing this until you get your girl.
