Why do folks who are not doctors care about how big the kid was?
The size of a baby used to be an indicator of whether or not that child would be healthy and live beyond childhood. Now, its for bragging rights; it is one of the usual bits of information that are passed on at birth, you know, the gender, length, weight, whether or not the baby was born w/hair and what color, etc.
Forgot to add: CONGRATULATIONS, MAN!!! You're in for it.