My EDD via my LMP is at 25/09/09...had my first scan at 11wks, gave me a EDD of 18/09/09...had my NT scan 2 weeks later, had my due date at 22/09/09, and my 18-22 wk scan, done at 20 wks, had me at 23/09/09....so I can safely say that my bubs is due anytime between the 18th and 25th of Sept....I usually split the difference and say the 22nd, but with my last 2 bubs, they were both post dates (my youngest being induced at 41wk + 3) so Im tipping I could go into October!

I got told by my OB that scans done from about 10 wks onwards will give you an accurate due date, but yeah, 10 days either side of that is pretty much the norm.