Normal children come in a dazzling variety of shapes and sizes, and their rates of growth and weight gain vary widely. A group of 8-year-olds, for example, may vary by as much as 30 pounds in weight and 8 inches in height without being considered abnormally tall, short, heavy, or thin, as long as their individual heights and weights are in proportion.
Pediatricians use standardized growth charts to determine whether children fall within the normal range, and they track each child’s growth rate over time. Another set of growth charts (for ages 0 to 2 years) has been developed by the World Health Organization, approved by the US Centers for Disease Control and Prevention, and recommended by the American Academy of Pediatrics for the first 2 years of life. Typically, pediatricians weigh and measure children at regular visits between birth and 3 years of age and then yearly after age 3. Heights and weights marked on charts provide a picture of the growth pattern.
However, weight or height alone doesn’t tell the whole story; a child’s weight in relation to height is what counts. A BMI below the fifth percentile is unusually low and needs a doctor’s evaluation, just as a BMI above the 95th percentile is high.