Accuracy of ultrasound dating

[Beneli]

I finally had my first scan today after slow rising (but then doubling) hcg results. I had to wait 3 gruelling weeks from hcg results until now! Went in completely ready for a blighted ovum (like my last mc) and didnt even bring my hubby (I was THAT sure). Low and behold, there was a perfect little bean flickering it's heart away at me! I then figured I would be told he would be measuring small, but told I was 4 days further along than my lmp. My question is, if I know when I ovulated because of ovulation kits etc, how could I measure any earlier? Which due date is more accurate (the ultrasound or my lmp)?

 

[jenniferttc1]

How far along are you? I think the earlier 6-8 weeks ultrasounds are much more accurate at dating a pregnancy than 12+ weeks. My son measured correctly at the early ultrasounds, but went up 3-4 days on the 12 week and 20 week scan. The further along you get, the more every baby developes at different rates.

 

[Beneli]

By my LMP I should have been 8w5d, but measuring 9w3d. I thought up until 12 weeks all babies were the same size so the ultrasound measurement is most accurate? Just doesn't make any sense to me how that could be!

 

[MissingBubs]

All of the measurements taken fit into the law of averages. Actually all babies grow at different rates at each stage of development. With my Daughter early scans put us back by 1-2 weeks meaning I tested positive at 3 weeks pregnant, 1 week before period was due! I tested because I was a week late!! Then at 12 and 20 week scan they she measured a week ahead of early scans. Then from 28 weeks onwards she measured two weeks ahead and they warned me she'd be 10lbs at 40 weeks! She was born 3 weeks "early" according to the date given at 12 week scan. That is the only one they stick with here in the UK so must be the most accurate.

I suppose what I'm trying to say is that baby is healthy and happy and will come when s/he is ready. Don't get too hung up on measurements.
And CONGRATULATIONS!!

 

[LJ88]

All of the measurements taken fit into the law of averages. Actually all babies grow at different rates at each stage of development. With my Daughter early scans put us back by 1-2 weeks meaning I tested positive at 3 weeks pregnant, 1 week before period was due! I tested because I was a week late!! Then at 12 and 20 week scan they she measured a week ahead of early scans. Then from 28 weeks onwards she measured two weeks ahead and they warned me she'd be 10lbs at 40 weeks! She was born 3 weeks "early" according to the date given at 12 week scan. That is the only one they stick with here in the UK so must be the most accurate.

I suppose what I'm trying to say is that baby is healthy and happy and will come when s/he is ready. Don't get too hung up on measurements.
And CONGRATULATIONS!!

Thank you for this reply. Giving me a little hope after my 1st scan which showed nothing! When it really should have showed something (thought I was 7+2 but they've said less than 6!)
Fingers crossed for next scan