O/T average head size of a 2 yr old???

I understand your concern. My four year old daughter was drug exposed, and her head circumference was always in the 5-10%. Whenever the doctor measured this, I would choke back tears, as it was a concrete reminder of her past. Still, the most important factor is if your child is following the growth chart. And yes, some kids just have smaller heads. BTW, my daughter is developing right on target. Keep your radar up but do your best not to become obsessed with it--good luck, it is a work in process for this mother!