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Big changes in growth centiles at 30 weeks

(8 Posts)
Judgybitch Mon 02-Dec-19 19:37:29

Hi Everyone, im looking for some reassurance ideally, We went in for a late scan today (30 weeks) to look for an inherited disease in my LG prior to birth. Luckily no sign of it but the sonographer redid her measurements while we were there and noted a big increase in both percentile for AC and HC (Abdominal and head circumference) AC went from above 50th to above 90th. HC went from below 50th to above 90th.

They have sent me for a glucose test in case of GD which could have caused the increase in abdominal size but i've had no other symptoms so hopefully not that, but thats being checked.

I however wanted to ask for your experience with if you have seen big changes in centiles and if things were fine/not fine as a result.

For context, my own head is quite big for an adult woman smile and both my husband and first born's heads are larger than average too. I know it isn't the big head that is the issue but the CHANGE that could be an issue. can anyone advise? I should have asked at the time but we were having a lot of info thrown at us.

TalkingIntoTheEther Mon 02-Dec-19 20:47:45

Hey OP,

My current pregnancy was 60th--ish centiles at 32 weeks (head and abs) and at 36 weeks was off the charts so quite a big jump. I got called in for a GTT which was negative for GD. I raised the issue of jumping up the centiles at the time of the scan but the Dr was unconcerned and said baby "is just following his own curve". I can't say it massively reassured me as like you I was under the impression that jumping up the centiles was reason to be concerned, but they said i didn't need to come in for another scan or anything.

One thing i read which reassured me a bit was that growth scans get less accurate as the pregnancy progresses, and although there is a 20% margin of error in either direction they tend to be overestimated.

Like you, DC1 has a big head (98th centile, confirmed at birth ouch!) She is absolutely fine, no developmental issues, but i never had any growth scans during that pregnancy so not sure if she jumped up the centiles at the end.

Good luck with your GTT.

Judgybitch Tue 03-Dec-19 08:48:40


Thanks so much. We will be having another growth scan in a few weeks to see if things are still going ok so will see. So yours was the same, with 'uneven' growth in some measurements but not others? My consultant didn't seem particularly concerned but i don't know if that is just how they are regardless or there really wasn't much to be worried about.

Its annoying as the scan was an extra one and if we hadn't gone we would still be in blissful ignorance!

CFlemingSmith Tue 03-Dec-19 09:01:22

Just regarding growth scans, from personally experience they're a load of bullsh*t
I had 4.
One said baby has a larger head when compared to body
The other 3 said my baby was classified as 'tiny' as under the 10th centile and to expect to give birth to a 3-4lb baby

I had a 8lb2oz perfectly formed baby. Every single scan was wrong.

Liverbird77 Tue 03-Dec-19 10:14:02

They said my baby would be huge...upper 90s. The sonographer was gurning and wincing and put the fear of god in me.
Baby came. 25th centile.

TalkingIntoTheEther Tue 03-Dec-19 11:34:42

Yeah I feel that frustration too with the 'extra' scans, it seems like such an inexact science that the results can't do much except cause a generalised anxiety. Although I guess if i had tested positive for GD I might be feeling a bit differently, and I think for babies who are measuring small the risks are more significant so the scans have more use.

My midwife told me some of the policies and guidelines regarding growth scans have changed recently making women more likely to be referred for one, which makes sense as I didn't have any additional scans with DC1 who was essentially a human Mrs Potato Head. I'm glad i didn't know before going into labour with her as like a previous poster it would have put the fear of god into me.

And just to echo what the other posters have said, the Dr that reviewed my scans said there is such a variation between sonographers that you are likely to get a significantly different measurements depending on who scans you.

Judgybitch Tue 03-Dec-19 11:41:22

@CFlemingSmith smile

Thanks all i feel reassured. Not particularly worried about a big head as my sons was larger then average and i was fine, normal birth with no issues (other then a massive vagina apparently smile)

Does anyone know if they take sex into account when calculating percentiles? Girls are generally smaller so is her head large for a girl or large for a baby !!!

Also is GD likely at this stage? i had a urine test two weeks ago that was fine. Had a normal pregnancy last time with no issues and no GD. is it likely to show up at 30 weeks in a second pregnancy with (literally) zero risk factors?

TalkingIntoTheEther Tue 03-Dec-19 12:09:00

I think the centiles are an average across both sexes.

from what i understand its not unheard of for GD to get flagged up at this stage, and the urine tests aren't accurate for excluding GD (although presence glucose in the urine sample can indicate a need for the GTT). But the fact that you have no risk factors bodes well. The Dr that saw me told me its just hospital policy to tests for GD with big babies, she initially said i didn't need the test as there were no other clinical indicators to suggest i had it, but then a midwife overruled her and got me in.

I wouldn't worry too much, but better to rule it out. Pain in the arse fasting for it though.

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