I believe there is someone here with a TB x welsh cross? I may be wrong on the breeds though. It's entirely possibly, and the foal wouldn't grow bigger than the ****'s uterus, but mini's usually have complications with pregnancy and birth anyway. I'd say if anything happened it was due to that. The foal would just grow faster once it was born and may have troubles nursing, but other then that I don't see alot wrong with it other then they would probably have a crappy conformation.
Baby, Sparta, Carmen, Henry, Hooch, Mercedes, Butterscotch