Some people hear there is an association between the stomach feeling hard and pregnancy. But the only time pregnancy is indicated by a hard stomach is when many months have passed and the baby has gotten big enough that you can feel his head or foot or bottom with your hand. It doesn't happen when you are so early that you don't even know if you're pregnant.
The baby has to be as big as a grapefruit or cantalope before your stomach feels more taut as a result of it being there. That does not happen when you are still so early that you have a pregnancy test say 'negative.'
Hard stomach so early go to a doctor to make sure it's not a stomach virus my stomach didn't start getting hard until I was about 20 ish weeks