(didn't read replies!!)

My OB told me that if you did a scan every month for your entire pregnancy you would get 9 different EDD.
He would only go by LMP. Which is fair enough. DD had severe IUGR and the only way we knew how far along I was was LMP.

Go by your LMP. Don't worry about scan dates.
JMO

Not sure i totally agree with this in all instances. I've always had way out there cylces so with DS1 i fell after coming off the BCP around the 2nd month but he was pushed back 4 weeks if looking at LMP dates and with DS2 i was on 42 day cylce so that pushed my dates back 2 weeks but i must admit i was a surprise to fall on a 28 day cycle this time... So i think unless you know your cylces which for DS1 i didn't (bit dumb back then) think i would tend to go with an early scan date.