Small head size with normal growth rate

Hello,
I would appreciate your opinion on this question. My son was born 4 weeks premature with 12.5 inches head circumference.  Since then, he has experienced normal growth rate of his head circumference, but still tracking at 1 to 3rd percentile on the growth chart.  Now at 16 month, he remains at just below 3rd percentile.  He sat alone by 7 months and walked independently at 15.5 months; his developmental milestones are felt to be reached normally.  It's important to mention that his grandfather and aunt both have small head sizes, but his parents seem to have normal head sizes.  Do you think that my son has a good prognosis?  Is there a cause for concern with small head size, but normal growth rate?  Is there anything else you recommend?  Thanks!

[Yao Sun, MD, PhD]

Small head size can be due to a variety of factors, including: familial (as you mentioned above), growth restriction during the pregnancy from maternal or placental conditions (for example, maternal hypertension or abnormally placed placenta), prenatal infections, and brain structural abnormalities.  The risk for long term neurodevelopmental problems depends to some extent upon the underlying cause.  Your pediatrician may be able to give you a better assessment of possible causes based on your pregnancy history and any evaluation that was performed on your son after he was born.

It is reassuring that your son's head is continuing to grow along his curve, and that his development has been within normal limits so far.  Your pediatrician will continue to follow his development closely with you.