How to interpret growth charts

From babyhood, height, weight, and head circumference often take center stage during well-child visits, and body mass index (BMI) is added to the lineup from age 2. These measurements, related to the age and gender of your baby, help health care providers determine whether your child’s growth is on track. But what are those “growth charts” that pediatricians rely on, and how did they come to be the standard on which your child’s statistics are plotted?

Pediatricians in six countries, including the United States, use the World Health Organization growth charts as a standard to show how healthy children should grow. The US Centers for Disease Control and Prevention (CDC) recommends that the WHO growth charts should be used with all children up to age 2. Health care providers then use the CDC growth charts to measure standard weight and stature in children and teens ages 2 through 19.

Both charts interpret a child’s growth using percentiles. The higher the percentile number, the bigger your child is compared to others her age. If your child is in the 50th percentile in height or weight, it means she falls right in the middle of where others her age stand. 

When should I be concerned about my child’s growth?

Unlike achieving a high score on a college entrance exam, being in the 95th percentile on a growth chart is not inherently better than being in the 10th percentile. Each child’s growth should be measured on his own chart over time, with attention paid to changes in the growth rate—as long as growth is steady and upward, a child who measures along the 14th percentile may be as healthy as a child who grows along the 74th percentile—as well as overall development physically, mentally, and behaviorally.

Health care providers generally find it concerning when a baby’s percentile changes significantly over a short period of time, as that may be a sign of a medical issue. Also, if a baby’s head measures much smaller than average, a health care provider may check that the baby’s brain is developing properly. A much higher than average head measurement may also warrant a medical evaluation to make sure there is no serious medical issue such as excess fluid in the brain.

Ultimately, growth charts are tools—one that should be used as part of a complete set of diagnostics to determine adequate and appropriate growth in children. A growth chart alone is not enough—family growth patterns and other indicators of good health and wellbeing are equally important. 

The growth charts 

  • Birth to 24 months: Boys Weight-for-length percentiles and Head circumference-for-age percentiles 
  • Birth to 24 months: Boys Length-for-age percentiles and Weight-for-age percentiles 
  • Birth to 24 months: Girls Weight-for-length percentiles and Head circumference-for-age percentiles 
  • Birth to 24 months: Girls Length-for-age percentiles and Weight-for-age percentiles 

Additional charts for beyond 2 years of age are also available on the CDC website.

Last updated November 20, 2020

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