Head circumference is a measurement of a child’s head around its largest area -- it measures the distance from above the eyebrows and ears and around the back of the head.
During routine check-ups, the distance is measured in centimeters or inches and compared with:
Past measurements of a child's head circumference
Normal ranges for a child's sex and age (weeks, months) -- based on values experts have obtained for normal growth rates of infants' and children's heads
Measurement of the head circumference is an important part of routine well baby care. During the well baby exam, a change from the expected normal head growth may alert the doctor of a possible problem.
For example, a head that is larger than normal or that is increasing in size faster than normal may be a sign of several problems, including water on the brain (hydrocephalus).
A very small head size (called microcephaly) or very slow growth rate may be a sign that the brain is not developing properly.
Kimmel SR, Ratliff-Schaub K. Growth and development. In: Rakel RE, ed. Textbook of Family Medicine. 7th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 31.
Jennifer K. Mannheim, ARNP, Medical Staff, Department of Psychiatry and Behavioral Health, Seattle Children's Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.