The normal value of head circumference is indicated as percentile >=2 and <98. The above value of head circumference is indicated as >98 percentile.
Explanation:
The average head circumference falls between 22 and 23 inches. The head circumference smaller than the normal value is said to be Microcephaly.
Head circumference is the one which is greater than two standard deviations(SD) or above the mean or greater than 98 percentile is said to be Macrocephaly.
Note:
Percentile <2 : Microcephaly
Percentile >=2 and < 98 : normal head circumference
percentile >=98 : Macrocephaly
