First and foremostely, I agree that an EDD is definitely an estimate and nobody - particularly medical experts - should get toooo hung up on the date.

With DS, my earliest scan was around 5w4d (from memory anyway, it was before 6w whatever the case), and they gave his EDD as 19 March 08. My next scan at 12w3d gave the 16 March 08 as his EDD. My Ob always went by the first scan. But guess which day DS was born ... 16 March 08.

Andie