Understanding Child Growth Charts and Percentiles

Pediatrician checking height of girl
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Growth charts help pediatricians figure out if children are growing and gaining weight well. Growth charts can also make it easy for parents to follow their children's growth. Learn how to use these charts and understand what percentiles mean for your child's progress.

After measuring your child's height, weight and head circumference at each routine well child check up, your pediatrician will plot them on a growth chart to see if your child is growing normally.

Although parents typically focus on whether a child is at the top or bottom of the growth charts, your pediatrician will likely be more interested that:

  • Your child is following his or her growth curve
  • Your child is not crossing percentiles

But remember that instead of just looking at a fixed point in time, the information about how your child is growing over time is what's important on a growth chart.

Growth Chart Percentiles

The percentile number means that your child exceeds that percentage of children his age for that measurement. If he is in the 75th percentile for height, he is taller than 75 percent of other children his age. If he is in the 25th percentile for weight, he only exceeds 25 percent of children his age in weight.

Instead of simply wanting to know if your child is growing well and following a growth curve, most parents want to know where they are on the growth curve. Are they at the top, bottom, or in the middle?

 Growth charts available from the CDC online make it so that you don't even have to wait until your next check up to see how your child is growing. Do you know how to calculate your child's percentiles for height and weight from a growth chart?

Reading Growth Charts

The first step is to find the right growth chart.

In this example, we are going to find the percentile for a 2-year-old boy who weighs 30 pounds, so we will use the growth chart for boys from birth to 36 months. The charts have the age at the top and bottom of the grid and length and weight at the left and right of the grid. Curves on the chart indicate the percentiles for length-for-age and weight-for-age.

  • Step A: Find the child's age at the bottom of the chart and draw a vertical line on the growth chart (from top to bottom). For this example, we would draw a line through 24 months (2 years).
  • Step B: Now find the child's weight on the right-hand side of the chart, 30 pounds in this example, and draw a horizontal line (from left to right).
  • Step C: Find the spot where these two lines intersect or cross each other.
  • Step D: Find the curve that is closest to this spot and follow it up and to the right until you find the number that corresponds to your child's percentile.

In this example, you can see that a 2-year-old boy who is 30 pounds is at the 75th percentile for his weight. What does that mean? It means that he weighs more than about 75 percent of boys his age. It also means that 25 percent of 2-year-old boys weigh more than he does.

Is that normal? Yes, if this boy has always been at the 75th percentile, he is continuing to grow at the rate expected.

Finding your child's percentile is a little harder if the curve doesn't actually pass through the spot where your child's age and weight come together. For example, what would you do if the boy in our example actually weighed 31 pounds? You would use all of the same steps and have to imagine a curve that is somewhere between the 75th and 90th percentiles, figuring that he was at about the 80th to 85th percentile.

If your child is above the 95th or below the fifth percentile, then you will also not be able to find an exact percentile, except to say that he is above or below the growth chart.

You can use the same steps to plot your child's height and body mass index.

What Do Percentiles Mean?

It is important to understand that the growth charts are best used to follow your child's growth over time or to find a pattern of his growth. Plotting your child's weight and height at different ages, and seeing if he follows a growth curve, is more important than what his percentiles are at any one time.

Even if your child is at the 5th percentile for his weight (meaning that 95 percent of kids his age weigh more than he does), if he has always been at the fifth percentile, then he is likely growing normally. It would be concerning and it might mean there was a problem with his growth if he had previously been at the 50th or 75th percentile and had now fallen down to the fifth percentile.

Also, remember that children between the ages of 6 and 18 months can normally move up or down on their percentiles, but older children should follow their growth curve fairly closely.

Types of Growth Charts

The growth charts developed by the National Center for Health Statistics were updated and revised by the  CDC in 2000. But there are also growth charts from the World Health Organization (WHO) that reflect an international standard (developed in 2006),  and growth charts that focus only on WIC-aged children (2012).

There are also growth charts for premature babies and children who are born with specific conditions, such as Down syndrome, Prader-Willi syndrome, achondroplasia, Marfan syndrome, etc. The Magic Foundation offers specialized growth charts for children with Noonan syndrome, Turner syndrome, Russell-Silver syndrome, and more conditions.

Which growth charts should most parents use? In general, you should use the WHO growth charts up until age 2 years and then use the CDC growth charts.

Growth Charts Online

That there are multiple sets of growth charts available for newborns, infants, and toddlers is likely to confuse many parents.

Just remember that the CDC advises that parents use the WHO growth charts until age two years, available from their website. The CDC growth charts can be used for older toddlers, although they are available for infants too. They can be used for older children and teens, from age 2 to 20. If you prefer, the CDC also has growth charts that start with the fifth percentile. They are available in English, Spanish, and French from the CDC website. WHO growth charts are also available for older children on the WHO website.

A Word From Verywell

You may be excited to follow your child's growth and development, but growth charts are just one tool. If you are concerned about your child's percentiles or see a large change from one appointment to the next, discuss this with your pediatrician. Work together to ensure healthy growth for your child.

Sources:

Grummer-Strawn LM, Reinold C, Krebs NF; Centers for Disease Control and Prevention (CDC). Use of the World Health Organization and CDC growth charts for children aged 0-59 months in the United States. Recommendations and Reports. MMWR Recomm Rep 2010; 59(RR-9);1-15.

Use and Interpretation of the WHO and CDC Growth Charts for Children from Birth to 20 Years in the United States. CDC. https://www.cdc.gov/nccdphp/dnpao/growthcharts/pdfs/growthchart.pdf. Updated May 2013.

WHO Multicentre Growth Reference Study Group. WHO Child Growth Standards: Growth velocity based on weight, length and head circumference: Methods and development. Geneva: World Health Organization, 2009.

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