Assessing Healthy Weight in Children: BMI History Tells the Tale
By Ann Johnson, RN, MSN, CSN
An important responsibility of pediatric health care providers is to monitor a child's growth and development. Variation from expected growth patterns is often the first indicator of poor nutrition or an undiagnosed disease, illness or genetic disorder. In 2000, the Centers for Disease Control and Prevention (CDC) released a new set of growth charts to evaluate child growth and development. These charts included the traditional measures of height and weight as well as a new tool to monitor the body mass index (BMI) of children ages 2 to 20 based on their age and gender. Tools to calculate BMI and plot BMI percentile are also available on the Shape Up America! website.
Both the Institute of Medicine1 and the American Academy of Pediatrics2 have recommended the use of annual BMI assessment as a valuable tool in the early identification of excessive weight gain in children. Because obesity is difficult to treat, early intervention in overweight children is critical. A National Institutes of Health study found that overweight in early childhood increases the chances for overweight in later life and debunks the myth that children will outgrow their excess weight as they get older.3
BMI is a reliable indicator of body fatness in children. It is calculated from a child's weight and height and the BMI number is then plotted on a gender-specific CDC BMI-for-age growth chart. This provides a percentile ranking that compares a child's BMI to that of other children of the same age and gender. For example, a BMI-for-age percentile of 75% means the child's BMI is greater than that of 75% of other children of the same age and gender.
This table lists the four categories of BMI-for-age percentile recognized by the CDC and shows how each category corresponds to the child's weight status:
| Percentile Value | Weight Status |
|---|---|
| Less than the 5th percentile | Underweight |
| 5th to the 85th percentile | Healthy weight |
| 85th to less than the 95th percentile | At risk of overweight |
| Equal to or greater than the 95th percentile | Overweight |
Calculating and graphing a child's BMI is a useful tool in identifying unusual increases in weight relative to growth in height. The accompanying graphs demonstrate five different growth patterns and illustrate how BMI growth charts can be utilized to identify the need for preventive counseling and intervention. These charts were designed utilizing the CDC's Epi-Info software (www.cdc.gov/epiinfo).
Ann Johnson, MSN, CSN, has been a school nurse in the East Penn School District for the past 9 years.
