Child urinates when laughing

When my 7 year old boy laughs, he urinates in his pants.  He has been doing this since he was around 5 years old.  Is this normal?  

[margypops]

he probably has a full bladder and could use the bathroom more, very often this is the same as sneezing,hes relaxed the muscle that controls the function, the bladder relaxes and he leaks some urine,he will probably out grow it, tell him to go 'pee' more ...

[Chazz77]

3% of young children have this problem. I had this problem when I was a child also. I read that it is hereditary. I learned to control myself around the age of 12. The problem now is I hold it longer than I should. Your child should go to the bathroom more often at this time. I find they try not to or they have issues with going to the bathroom more than most. But this is what needs to be done until a later age. I am curious if someone else in the family had this problem as a child. I would more importantly see her or his doctor and run test to make sure it isn't more than what it is.