Are 4D scan dates more accurate than 2D scan dates?

[flubdub]

I had my 12 week, 2D scan a few months ago, and they gave me my date (28th April), and at 18 weeks, I had a private 4D scan, which said the baby was measuring 6 days bigger than the hospital said (which would make his due date 22nd April), but she wasnt going to change my dates.
My bump measurement has been spot on average until last week (37 weeks) where he was just slightly bigger than average.
Which date was more likely to be accurate? The 4D scan or the 2D one?

As for as I know, measuring in the first trimester is in a way more accurate, as all Embryos grow at the same rate. But I might got that wrong....

agreed - first tri scan are always the most accurate

i'm with the others, your first date more likely to be the right one. having said that, baby will turn up precisely when he wants just to make sure you know who's in charge

by the way....6 days either way will not really make much of a difference....