I've measured further along with all my pregnancies, but the most accurate is your first u/s if it's done around the 8-10 wk. mark. Everything after can be off by quite a bit, so they don't rely on it for your due date. Both my babies were on the slightly big side (9 lbs. and 8 lbs. 2 oz) and I delivered 1 wk. early with both, but I don't think it's anything to worry about unless you have gestational diabetes and then they may induce you earlier if the baby is getting too big. I wouldn't worry about it
