Monday, December 10, 2012

Brain Growth (via Head Circumference) at 18 Months

Head Circumference

While it might be somewhat of a myth that big heads equal big smarts (at least for adults), studies have shown that head growth (as measured by head circumference) in infancy is predictive of later intelligence.

My son Damien started out with a perfectly average head circumference at birth (50th percentile), but within one month his head circumference jumped to the 80th percentile, and gradually crept its way upward throughout his first year, reaching the 99th percentile by his first birthday.

Now, at 18 months, his head measured in at a whopping 20.5 inches, and the "99.9th percentile", and is officially "off the charts" (literally).

I guess it's nice to know that the enrichment things we have been doing have been paying off!

"In the morning it flourisheth, and groweth up..." Psalm 90:6
Damien is 18 months old


  1. 2012/12/10 at 9:44 pm

    Thank you for posting this. My doctor had me concerned about my lo head size. He went from 10th percentile at birth to the 97th at his 4 month check up. His head doesn’t look abnormally large and has plateaued in the high 90s so they stop being concerned. This though makes me wonder if EL was one of the contributing factors lol.

  2. 2013/05/19 at 6:53 pm

    It’s comforting to read this post for me! Our daughter is 18 months currently and her head measures 19.75 inches — way off the charts. She also started off in the 50th percentile at birth and jumped to around the 80th and then up around her 1st birthday. Our doctor is sending us to get an MRI, though �� I’m really hoping + praying it’s just as you mentioned — a sign of intelligence. She’s definitely got a lot of smarts at this young age. Anyway, just wanted to say thanks for sharing a similar story of head size that doesn’t make me worry something is wrong with my child!

  3. 2016/02/02 at 2:51 pm

    As the owner of a large head myself, and the mother of two young gitls (18 months and 3 years old) with large heads (both hovering right around 100% consistently from birth), I would urge you and your readers to not dismiss concern regarding head size from your pediatrician. It could be an indicator of issues and one that should not be ignored. Especially if there is a change in their chart path (e.g., 50% then jumps to 90% at next appointment or vice versa). We just don’t ever want to ignore something that could be serious.


Thank you for your comments!