HC/AC on the 30th centile - normal??

[mynameismynameis]

am slowly going crazy...

I have regular growth scans because first they said "the head is small" (i was very worried!), then they said the AC (abdominal circumference) is small too.

Well, today was another scan and they put the disclaimer in my notes: "mother is aware that ultrasound alone cannot exclude all genetic syndromes and chromosomal abnormalities..." (this freaks me out.)

I had several different docs scanning the baby and none of them was "concerned". Still of course no-one can exclude genetic problems..

Well, my question is: a head circumference/abdominal circumference (HC/AC) on the 3oth centile is kind of normal, right?

thanks for reading, please help!

30th is fine: the whole point of centiles is that they range from 1 to 100. So out of 100 babies, 29 will be smaller than yours. So small, but not the smallest.

And the disclaimers sounds bog-standard to me. My scan notes said that after a very detailed scan with nothing abnormal found at all (the sonographer described our baby as 'lovely looking').

Not only normal but nearly average!?

My baby's head circumference on 20 week scan didn't even get on the scale, I mean it is below the 1st centile...but this is my 3rd baby and the other two have both had small heads so I'm not concerned and no one else seemed to be either, abdominal circumference was below 50th. I would think it's only if you had tiny head measurement versus larger abdominal measurement they would be worried, or if the measurements were not increasing as time goes on (you said it was a growth scan so presumably as long as each measurement has shown growth since last time they will be happy with it?

how many weeks are you and how regularly are they scanning you?

I don't understand why they're scanning you purely due to a below average but perfectly normal HC and AC. Are there not any other reasons for scanning you?

My DD always had a biggish head, above 75th centile when I was pg. Her head has always measured around 91st centile at the different checks since she was born. So I was surprised at my 20 week scan with DC2 for the head to be measuring around the 25th centile. But it's still perfectly normal and they never questioned it at all.

abcde1 - thanks for being level headed and calming me down :-)

brettgirl - yes, average is exactly what you want in an ultrasound. Thanks, i needed to hear that!

mrswoz - yes isn't it freaky to see the little size marker way off the size chart. It totally got me. Your baby sounds similar to mine, only that you expected your baby to have a smaller head. My 2 kids measured perfectly average. Measurements are increasing on my baby's head and belly, and belly is small too. So you are right, IT IS JUST A SMALL BABY. That is also what the consultants have told me... They are scanning me every week from 32 weeks, one week they measure brain blood flow, Dopplers and Placenta and every two weeks they do a growth scan (and said "constant growth velocity"). Am 36 weeks now. They have been on the case, I have to say. I think it is because at one point they suspected the Placenta to be malfunctioning and the fluid to be low.

ItsMyLastOne - They are scanning me because I really made a fuss about this. I agree, a head around the 25 centile is no reason for concern, that wouldn't bother me either, it is only when you go off the charts with one or two measurement (like the head in my baby's case) that it could show problems.

My baby's head measured on the 3rd centile and the belly is roughly on the 30th centile. This results in a pretty average ratio of HC/AC. Luckily.

I am rambling.

thanks Ladies