My experience with this bug was a very bizarre one. I had a save file from only a couple sim hours after one of my DecaDynasty heirs moved to the next house. The heir, Kerri, was not yet pregnant. The family aged fine until Kerri gave birth. This happened on three separate occasions, each time I went back to where Kerri had just moved--without having even woohoo'd. I also have done all of the things Rachel has done, but nothing worked. The game has since been deleted entirely, but I would also like to know if there is anything to do to prevent this or fix this in the event of encountering the glitch again.