What was more accurate - your 12 week or your last period due date?

[Squibble84]

Just out of interest?! My LMP due date is the 2nd September, the 12 weeks scan moved it to the 6th September - what was more accurate with your previous pregnancies?

I would believe the scan rather than LMP, I'm an extreme example but a long cycle means LMP puts me two weeks ahead of where I really am.
Having said that I had a scan yesterday and she said they have a 2 day margin of error either way so your dates really aren't that different.

My lmp and scan dates differ by 1 day, scan dates me one day earlier than lmp does.

All medical staff use scan date so I'd assume it is more accurate.

As I have gone further past my due date from the scan I would say LMP, currently 6 days over. Though the scan did date me before my LMP so that probabky makes a difference. Expected at my early scan (8wks) to be told I wasn't as far gone but was told further so really not sure when I conceived.