Any sonographers/midwives/obstetricians or other foetal experts out there?

[EGH]

Wondering if anyone can calm me down..
I had a private scan at 18+6 weeks and all was fine generally but when I got home and read the scan report it measure the FL in 43rd centile, HC 50th centile and AC 83rd centile. Wasn’t too concerned. Fast forward and I went for my NHS scan at 20+3, this time FL in 28th fentile, HC 73rd and AC 95th.
sonographer referred me for gestational diabetes but no comments on the other measurements.
I think if I looked at either of these scans isolated, I wouldn’t be concerned, but it seems that the head and abdomen are growing very quickly and the femur length is slowing down. Stupidly I started googling and feeling very anxious now that there could be a more serious problem with baby such as skeletal dysplasia or dwarfism.
does anyone know much about this topic, do they do other checks at 20 week scan that would identify one of these conditions? Is it normal for there to be such a variation of centile between FL, HC and AC? How accurate are these measurements?
having had two MC before this pregnancy I’m a real worrier and have convinced myself there is something wrong with the baby 😞

Although we should all be measuring the same images, unfortunately there is often a difference in how sonographers scan and the image quality can be significantly affected by the position of baby on the day. Really not anything to worry about in terms of the difference in measurements.
In terms of the AC on the 95th centile, it's very easy and unfortunately very common to over-estimate these measurements. The GTT will test for diabetes - if that's ruled out (which is very likely) then there's no reason why your baby would be growing bigger than they should be. Hope that helps!

Bear in mind as well, that baby isn't growing everything at the same rate. Everything grows in spurts, and not all at the same time. Could be the legs had just had a spurt at your private scan, and hadn't had another at your 20 week one.

But the most likely explanation is, as Cheery says, it's probably down to the position of the baby causing a substap

Easier said than done but try not to worry. All these measurements fluctuate (both the baby changing and the sonographer’s technique). Also depends on how active they are/what position they were in etc.

Most anomalies are picked up at the 12 week scan (this was the case with my second pregnancy) and GD around 28-32 weeks (this was the case with my first pregnancy).

No news is good news, try not to google. The doctors and midwives have seen it all and will always err on the side of caution and flag any issues to you. Sending love.

Thank you everyone! I do feel reassured I just got myself in to a bit of a panic yesterday! Thanks again x