12 week Scan science

[Charingcrossbun]

Hi ladies,
I am all scanned, weight, measured, pricked and official!!
They have chopped 2 weeks off my dates (saying I'm 12 weeks not the 14 weeks I thought I was). Which doesn't really matter at all but it feels weird, have nothing new to read in my baby book and look really fat for 12 weeks!
Still Am I allowed not to have been too impressed with the science of the scan? She made me wiggle around to get bump to stretch out from it's ball then measured "crown to rump" "11weeks 5days" the more I wriggled the longer bump got - I reckon if I had done a few star jumps I could have got an extra week added!
Anyone else feel this?

She measured the foetus, not your bump - is that what you mean?

That's what they do to measure the baby. When I went for scans they had me jumping up an down on the spot, coughing, lying on my side, going for a walk then coming back in etc.

On one of my 20 week scans we couldn't get baby to change position at all, he'd just kick but not turn over, so I had to go back 2 weeks later and be scanned again so they could get correct measurements x

If baby wasn't uncurled enough to measure properly then they would have got you back for a rescan.

Thanks ladies, you are all right - I'm not worried about the scan. I was just surprised that the scan give such an exact age with such a simple measurement. Not sure what I was expecting I suppose I just thought they'd take several different measurements and use them to calculate the age. Still doesn't matter it was alive and kicking and that's what matters!

The foetus grows at a regular rate for the first few months so taking a crown to rump measurement gives them an accurate assessment of its age.

If it helps they measured both of mine further along because they measured long. I know this could not have been the case with dd as my husband wasn't in the country at the time to conceive when they said I did. Im tall so would make sense that they would look further along. Both where overdue and induced and I think this was down to incorrect dates at the 12 week scan.