20 week anamoly scan and Head Circumfrence 169.5

[Helpdesk3]

Hi,

I had my 20 week anomaly scan and the babies head was measuring 169.5 which is only 17th centile.

Everything else was around 50th centile.

I am concerned, can the babies HC catch up as gestation progresses? Any specific causes for smaller HC?

Any feedback would be greatly appreciated

Sorry no advice but did the doctors seem concerned?

Please don’t worry. Many, many women have scans were the measurements aren’t all within a centile or two of each other - my daughter’s legs were something like 11th centile, and her head on the 60th or so. She’s perfectly healthy (with a normal head and quite long legs now!). I know it’s tempting to analyse every bit of info, but try to relax - they really would tell you if there was cause for concern

No they said its within the 5th and 95th range. Just want to know if other women had a low head circumference around 20 week and reached higher centile towards end of pregnancy.

If the sonographer was concerned in any way they would have reffered you immediately to fetal medicine for another scan.

@ShushShushShush

If the sonographer was concerned in any way they would have reffered you immediately to fetal medicine for another scan.

This. They are pretty cautious, and anything that might be a cause for concern would be referred. If they didn't seem concerned, then it's within normal bounds.

How accurate are the HC measurements at 20 weeks?

I had similar. head in 20th percentile, legs in the 78th and everything else around the 35-40th percentile. The sonographer said nothing to worry about. i spoke to the midwife too and she said it really isn't anything to be concerned about, they change on a daily basis and as long as within normal range it's fine.

My best friend had growth scans every two weeks and her baby's head apparently shrunk between scans (she was born perfectly healthy) so don't think it's particularly accurate

My main concern is lower head circumference correlates to lower brain development. Would this be the case?

I promise you, if the sonographer thought that there was even the slightest awry, they would have reffered you to fetal medicine. They don't take chances with babies health.

They will have fully checked and double checked your babies brain and the measurements.

Midwife sonographer here.

17th centile is well within normal range, no cause for concern at all. Like us, babies come in all shapes and sizes and very few of us would have all of our measurements exactly ‘average’

@MojoJojo71 how accurate are the HC measurements using ultrasound.
I'm thinking of private to get it reconfirmed

@Teapiggies

Please don’t worry. Many, many women have scans were the measurements aren’t all within a centile or two of each other - my daughter’s legs were something like 11th centile, and her head on the 60th or so. She’s perfectly healthy (with a normal head and quite long legs now!). I know it’s tempting to analyse every bit of info, but try to relax - they really would tell you if there was cause for concern

My DD was similar she had a 98th percentile head circumference at birth (ow!) and stumpy limbs (femur length was just within limits on my 33 week scan), she looked out of proportion for the whole first year, but now she is 3.5 she is totally in proportion. Didn't help that she was very slow growing hair so this just highlighted her massive head!!

The accuracy would depend on factors such as fetal position and BMI but all sonographers are trained to obtain images in the same way as required by the fetal anomaly screening program and if the sonographer had been unable to obtain an accurate measurement they would’ve arranged for you to come back for a re-scan. As a previous poster said, we take no chances with babies and always err on the side of caution.