Growth Charts: The History Behind the Curves

A key tool for anyone caring for infants and children are growth charts. The following excerpt provides some history behind growth charts. It comes from an article written by Aaron E. Carroll entitled, The Trouble with Growth Charts. It was published in parenting.nytimes.com on November 25, 2019.

The take home point for those of us in the United States: use WHO growth charts up to age 2, then use CDC growth charts.

“The first “national” growth charts were produced in 1977 and pulled weight, height and head circumference measurements from large cross-country health surveys. These data points provide the basis for the curves and percentiles parents have become accustomed to seeing in the pediatrician’s office. If your 6-month-old’s weight falls on the 75^th percentile, for instance, roughly 75 per cent of the 6-months olds across the country weigh less than the child and 25% weigh more. If her height is at the 90%, 90 percent of children her age are shorter and 10 percent are taller.

 However, the data upon which those charts relied on were suboptimal. Those national surveys, for instance, did not contain data for kids from birth to 12 months so experts had to turn to a different data source. The new source had one big problem – that being that almost all of the infants in the data set were formula-fed, white, middle-class infants living in southwest Ohio. There was no reason to believe that children with different backgrounds, ethnicities or diet would (or should) grow similarly.

In 2000, the Centers for Disease Control and Prevention (CDC) revised those charts to include more nationally representative information about kids in their first year. Then, confusing things further, the World Health Organization released its own version of growth charts in 2006 for children between 0 and 5, focusing on how kids should grow under optimal conditions (such as being breastfed and living in safe, comfortable, smoke-free homes). Because some experts believed that the W.H.O.’s charts for 0-2-year olds were better than those produced for those age ranges from the CDC, the CDC recommended in 2010 that pediatricians start using the WHO charts until children were 2, and then switch back to CDC charts after that. (The CDC charts go up to age 19, while the WHO charts go to age 5.)