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:

There will be some differences in classifications betwen the WHO charts and the 2000 CDC curves. For example, a head circumference of 45 cm for a 15-month old boy is betwen the 25th and 50th percentiles on the CDC chart; on the WHO curve, this is between the 5th and 10th percnetiles.

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).