20 week scan measurements

[TTCbaby2023]

Hi everyone,

I had a private scan at a fertility clinic at 16+4 weeks and measurements were all around the 50th percentile for head circumference, femur and abdominal circumference.
Fast forward to today for my NHS 20 week scan. She didn't find anything untoward and said at the end that the baby is growing beautifully, yet when I looked at the report when I left, the measurements are all over the place. HC is on 20th percentile, BPD 23rd, AC 86th (!!) and femur 52nd. Aren't these measurements a bit concerning?
She mentioned that her head was behind the belly button and I read somewhere that it can make it difficult to get accurate measurements. Has anyone ever heard anything like that?

Although she was very positive, I don't know what to make of it compared to 3 weeks ago...

Has anyone had similar experience and good outcome? Is this worrying?

Those measurements (at your 20 week scan) are very similar to what my DS' measurements were. I remember questioning it at the time, I was especially worried by his head measuring what seemed like a lot smaller than everything else. I was told it was nothing to worry about and he's now a healthy nearly 3 year old who's perfectly in proportion. I was told that when growing in the womb sometimes babies aren't necessarily in proportion and they usually level out the closer they get to their due date, but as long as they are on the percentile chart there isn't a reason to worry.

Fast forward to last month I had my 20 week scan for DD and got a referral to fetal medicine due to her having a head measurement on the 4th percentile while the rest of her measured between 30-50th percentiles. I had a blood test to rule out infections that can cause this and it all came back clear. Consultant reviewed my scan images and the sonographers notes and they were happy to discharge me with no further action as she is technically still on the chart and there were no other abnormalities detected. Through this experience I've learned that any measurement under the 5th percentile or over 95th warrants a referral for further investigation. Any other measurements are deemed within 'normal' range. The consultant also said that measurements can be tricky to get sometimes depending on baby's position (mine was breech which can make HC difficult to obtain), and being off even by a few millimetres can mean a big difference in what percentile they are placed under.

I hope the above helps you a little, and I totally and completely understand the worry you're experiencing on this - if you need to, ask to discuss the results further with your midwife or a consultant and they should accommodate this for your peace of mind. I'm sure your LO will be fine ❤️

@Lottie917 Thank you so much for sharing your experience, this is very helpful 😊. My baby was in breech position as well and the head was behind my belly button so she was struggling at some point to even see the brain properly.
I am seeing the consultant tomorrow morning as my care is consultant led so I will make sure to ask many questions and bring my notes with me.
We worry so much about our LOs whom we haven't even met yet 😊