What does it mean when you dream your parents have a new baby?

The "new baby" symbolically represents some person or thing that has recently come into your life. That new person or thing could even be something you hoped for, but now that it is present, you are finding that not all the changes it causes are welcome. Your parents in the dream probably also are symbolic. They could represent yourself - you may be the one that brought about the new circumstance in your life. This might be anything from a new friend to your new driver's license.