How accurate are early scans?

[yellowflowers]

I had wary scan at what I though was 7+1 an they said it was 7+0.

Then '12 week scan' yesterday at what I thought was 11+3 but they thought was 11+1 (so got to go back in two weeks for another). Which means it has lost a day between scans.

This is just normal margin of error though right?

Unless you had assisted conception you can't be sure of exactly when you conceived anyway, but even a week or so either way isn't any cause for concern. Babies grow at different rates. Don't worry :)

Early not wary

Sounds normal.to me. I had 3 scans in first pregnancy and got a different due date each time! First date was 31st may, second 6th June, third, 3rd June. Baby born on 11th June!

Same as Tara here, LMP put DD at 2nd August, scans (had bleeding so had multiple scans) gave me dates ranging from 27th to 31st July. DD actually arrived on 12th August

Totally normal and nothing to worry about.

I wouldnt worry over a couple of days.

I had three early scans (!) and each time I went "back" a day or two iyswim.

(So for example first scan I was told 6 weeks, then 2 weeks later exactly I was told 7+5, then 2 weeks exactly after that I was told 9+3).

Have now had my 12 week scan and all is absolutely fine, baby has been growing at normal rate. I think the rate of growth fluctuates a lot in the early weeks which is why they don't really try to date you till the 12 week scan. I have read that they can only accurately judge dates based on foetus size in weeks 11-13 (and even then it can be a few days off).

there's a margin of a couple of days I wouldn't think twice about it unless its almost a week

my early scan says I concieved a day or two before I ovulated :-S - it's close enough, but I put myself at 2 days later

A couple of days is totally normal. I had ivf with icsi so knew exact date and time of conception. 3 early scans were all one or 2 days out (measuring smaller) but then official scan at 12+1 moved to a day ahead to 12+2!
Consultant in earl scans showed me how small the difference was to move the dates by a day or 2. She explained there is always variation in measuring according to who is doing in the scan, the angle, how far the baby is from probe etc. Despite knowing exact dates, ivf pregnancies here are dated according to measurement at 12 week scan, so go with that! (another friend who conceived thru ivf was put back 2 days at 12 week scan, and her baby is doing fine!)

Thank you all that's reassuring