A growth chart is used to measure and compare a child's growth with what is considered normal for that child's age and gender. The nationally accepted growth charts are based on measurement data collected by the National Center for Health Statistics. They take into consideration height, weight, and head circumference.

Height and weight measurements are used to document a child's:

• Height or length (in inches or centimeters)
• Weight (in ounces and pounds, or grams and kilograms), based on age in weeks, months, and years

For children under age 3, height is measured while laying down. For children over 3, height is measured while standing. Height and weight measurements are recorded and graphed until the child is 17.

Head circumference is a measurement of the size of the head taken by wrapping a tape measure above the eyebrows and around to the back of head. For specific information on this topic, see head circumference.

Growth chart measurements are compared to the standard (normal) range for children of the same gender and age. The measurements are important because they may provide an early warning that the child has a medical problem. For instance, during the first 18 months of life and particularly during early infancy, abnormal growth of the head can alert the doctor to a problem.

Head circumference growth that is too rapid may be a sign of hydrocephalus (water around the brain), a brain tumor, or other conditions that cause macrocephaly (abnormally large head). Growth that is too slow may be a sign of problems in brain development, early fusion of sutures (the bones of the skull), or other problems.

Insufficient gain in weight, height or a combination may indicate failure-to-thrive, chronic illness, neglect, or other problems.

Abnormal growth as seen on the growth charts is only a sign of a potential problem. Your doctor will determine if it represents an actual medical problem or simply needs to be followed carefully. Because of individual variations in genetics and hormones, growth charts are not an accurate predictor of a child's future, full-grown height.