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.
Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW. Growth and measurement. In: Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW, eds. Siedel's Guide to Physical Examination. 8th. St Louis, MO: Elsevier Mosby; 2015:chap 6.
Keane VA. Assessment of growth. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 15.