WASHINGTON — For the first time in 23 years, the government is updating the charts used to track children's growth and adding a new formula to help identify weight problems in children as young as 2.
The charts, a staple in the offices of pediatricians and school nurses around the country, now include the body mass index, or BMI, a single number that compares weight to height. It's already used to track obesity among adults.
The new charts from the Centers for Disease Control and Prevention also should more accurately reflect the average height and weight of U.S. children from birth to age 3, because they are based on more recent and much more comprehensive data than the old charts for babies and toddlers. The changes are minor accept for the lightest and heaviest children, CDC officials said.
"One of the first questions people ask new parents is 'How much did your baby weigh?' " said Donna Shalala, secretary of Health and Human Services. "From that moment on, growth charts are a reference point for health professionals and parents as their children grow into adolescents and adulthood."
The new research found babies and toddlers to be slightly heavier and shorter than in the previous charts and also found infants in the first few months have larger head circumferences than the older charts showed.
For example, in a previous chart, a 3-year-old girl at the 50th percentile — or the chart's halfway point — would be 32.6 pounds and 38.4 inches in length. On the new chart, the 50th percentile is 33.3 pounds and 38.7 inches.
As a result, pediatricians will classify more babies as underweight and fewer as overweight, said officials at CDC's National Center for Health Statistics, which published the charts.
On the new charts, a 22.5-pound 2-year-old girl would be in the 5th percentile, which is considered underweight by many doctors depending on how long the child measured. On the old chart, the same child would have been in the 10th percentile, lean but not necessarily underweight.
The new BMI charts, which begin at age 2, are a more accurate tool for measuring obesity than older charts that included a measurement of weight according to height, officials said.
"This means parents have an opportunity to change their children's eating habits before a weight problem ever develops," said Shalala.
A 2-year-old boy in the 50th percentile, or middle range, would have a BMI of 16.5. A boy with a score of 19.8 would be in the 95th percentile — meaning the vast majority of boys his age have a lower BMI. Kids at the 95th percentile are considered overweight and those at the 85th percentile are considered at risk.
Obesity is a growing national health problem among both adults and children. Nearly one in five American adults are obese and the number of obese children has doubled in the past 20 years to about 4.5 million kids, or 11 percent of youngsters ages 6 to 17, according to the latest government studies.
Health professionals believe that catching the problem is important in preventing children from going on to have weight problems or becoming obese later in life.
The new charts use government data from the last three decades about formula- and breast-fed children from all racial and ethnic groups. The old charts were based on a private study during the 1960s and 1970s that looked only at white, formula-fed children in Ohio.
On the Net: The new growth charts can be found at www.cdc.gov/growthcharts