Maybe not normal, but it was for me! They always measured me like 5 times just to make sure they weren't seeing things, and I was always measuring at least 2 wks ahead. However, they say the most accurate u/s is the one before 12 weeks. Since all babies develop at the same rate before that, so that is how they determine age/how far. After 12 weeks, they all develop different. They kept begging me to do a c-section since they made me do an u/s at 38wks to "guess" how big he was, and they gave me an 8-12lb estimate! That's a huge difference. The babies are just too big to see their skull or femur lines to measure a definite age (that is how they measure), so they just can't get the exact. He ended up being 9 lbs 9 oz, we knew he was going to be big, but he fit through my pelvis just fine (sort of lol); and at least he wasn't 12 lbs! So, maybe he is bigger, or maybe you have a lot of fluid, they should be able to measure the fluid though. Either way, shouldn't be anything concerning as long as baby and Mom are ok. Good luck and remember, they wont make you do anything unless it is for the health of both of you.