1. Measuring and Plotting Head Circumference

To measure head size, we measure the circumference, using a tape measure. Details of measurement technique are given in the module, Accurately Weighing and Measuring Infants, Children and Adolescents: Technique.

Note the following points:

The differences between the 1977 NCHS Growth Charts and the 2000 CDC Growth Charts are most pronounced in the head circumference-for-age charts. In general, the 2000 percentiles are higher than the 1977 percentiles until age 4-6 months. At this point, a crossover occurs, and the 2000 curve becomes lower than the 1977 curve. When using the 2000 charts, there will be some differences in classifications relative to the 1977 charts. For example, with the 2000 charts, infants will be less often classified as having small head circumferences particularly after 6 months, and more often classified as having large head circumferences.

Measurements may be influenced by abnormal head shape.

Measuring the parents' heads may be helpful in interpretation because large and small head size can be inherited.

Growth patterns over time are more informative than measurements done once.

The head of a premature infant grows more rapidly than that of a term infant, so it is important to correct for gestational age and to consider using the special growth charts for low-birth-weight infants from the Infant Health and Development Program (IHDP) . For more information about correcting for gestational age, see the module, Overview of Growth Charts. For information about the use of the IHDP growth charts, see the module, The CDC Growth Charts for Children with Special Health Care Needs.

The CDC growth charts show head circumference up to 36 months.

For children up to 18 years, charts based on a composite, international sample have been standard for many years (Nellhaus, 1968).