Will my baby be unhealthy if is born over 9 lbs?

No. Just like there is a normal size range for adults, there are always going to be normal small babies and normal big babies. Babies born over 9 lbs are at risk for problems such as shoulder dystocia (which in rare cases can cause nerve damage) and low blood sugar at birth. Big babies are always closely watched for any problems that might develop, but almost always do great.
LGA babies... (large for gestational age) tend to have more problems with low blood sugar and low calcium, and need careful monitoring in the first 48 hours of life.
See below. Larger babies are more difficult to deliver due to size. Your OB doctor will be keeping an eye on you to make sure that you don't have any problems.