A child’s head circumference is usually measured for the first two to three
years during routine checkups. A soft tape measure is placed above the eyebrows and ears
and around the back of the head. The results are measured in either inches or
centimeters and then compared to previous measurements.
The growth of a child’s head occurs in response to the development of their
brain. It is “relatively” independent of body growth and nutrition. Genetic factors often
play a role in the size of a child’s head: for example, a father with a larger than
average head size might have a child whose head size is also larger than normal).The most
rapid head growth occurs in the first two years of life.
If a child’s head size is growing too fast and crossing percentiles on
the head circumference growth chart, the youngster should be watched closely for the
development of hydrocephalus (“water” on the brain) or other neurological
disorders. The growth of the head due to hydrocephalus may be quite rapid and expand at
the rate of more than one inch per month.
If the head circumference is above average, but continues to follow the
same percentile (for example, is on the 90 percentile at three months and the 90% percentile
at six months) there is usually no cause for concern.
On the other hand, a small head circumference, especially if it is not
following the same percentile is of greater concern (for example, the measurement is in
the 5th percentile at three months and off the chart at the 6 month checkup). This
“may” indicate a condition known as “microcephaly” and is often associated with
neuronevelopmental problems. The most common cause of microcephaly is inadequate
brain growth. Since the major stimulus for skull growth is brain growth, if
the brain is injured during its early development the result will be a small head. A
small head is only rarely secondary to early closure of the skull sutures and usually the
child has an abnormal head shape, not size. Just as with a large head, there will be
normal infants and children with head circumferences below the normal range.
We hope you find these head circumference charts useful in following your
baby’s growth and development.
Girls Head Circumference Charts
Boys Head Circumference Charts