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:
- Past measurements of a child's head circumference.
- Normal ranges for a child's sex and age (weeks, months), based on values that 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 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.
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Bamba V, Kelly A. Assessment of growth. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 27.
Riddell A. Children and adolescents. In: Glynn M, Drake WM, eds. Hutchison's Clinical Methods. 25th ed. Philadelphia, PA: Elsevier; 2023:chap 6.
Last reviewed on: 1/24/2023
Reviewed by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.