Interesting thread- our pediatrician told us early (when DS was about 3 months old) that head size was the best indicator of autism and that we'd have to really watch DS closely for the signs. They told us that for a whole year. He was born with a smallish head (and one month early and a very very long labor with a bad cone!) and ended up with a HUGE noggin. Huge. I buy adult size hats.

He also now just has a huge head...