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 checkups, the distance is measured in centimeters or inches and compared with:
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 health care provider 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.
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.