What if you dream that you are a mother at 13?

Nothing, you can't get pregnant by dreaming.

Dreams do not cause things to happen. You can only become pregnant if you have been having sex. So if you are a girl and you have had sex with a guy, it might be a good idea to get a pregnancy test.

If you have not been having sex, the dream about being pregnant only means that you are "developing" physically. The hormones that are causing you to mature into a woman also influence your dreams. It is very natural for all girls to dream about pregnancy and babies.