My dfs's head circumference is low. Microcephaly runs in his family and I'm trying to get as much information as possible about it. His pediatrician said he'll do an ultrasound next month when he's 6 mos old. Can anyone share an informative book and/or website that goes over some things to watch for? His head size is growing, just at a slower rate in percentage ratio to his body. We're working with EI for his developmental delays.