The scan I had at nine weeks was spot on for dates and I know exactly when we conceived, but at the 20wks scan he was a week ahead on dates, but we are keeping the original date as I too have a history of larger babies. Currently I am measuring about 5 weeks ahead, but that is purely because of his position - his head is way up the top and sits quite high - so it would be silly to change dates becuase of that.

I'm with Deb on this one and would go with the 9wks scan.