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How to Read a Growth Chart: Percentiles Explained

​When you go to the pediatrician for a well-child check, you'll always review your baby's or child's growth. It's probably the most important piece of data your pediatrician gets. The reason is, it can capture so much about your child's vitality.

Growth Chart Downloads:

WHO Growth Charts

CDC Growth Charts

First 3 Years – A Major Growth Period

In the first 3 years, we use one growth chart that looks at the head's circumference and the weight and length. It's based on gender and lots of data. We watch for changes in the size of head circumference in infancy because we want to know that the brain is growing. Growth grids have been used since the 1970s, but back in 2000, they were revised to really reflect different cultural and ethnic diversities that exist within our population.

Why Percentiles Are Not Like the Grades in School

What we want from a growth grid is to really map out the ideal growth for children. This isn't like grades in school. When your child comes in at the 10th percentile, it's really no better or worse than coming in at the 90th. What we care about most is the trend at which your baby or child gains weight, height, or head circumference.

After age 2, you can use the growth chart to expand between the ages of 2 and 20. In addition to weight and height at that point, we also look at body mass index, that number where we try to capture how children's proportionality is. Are they at risk for overweight or are they too lean?

Everything from genetics, to environment, to nutrition, to activity, to health problems really influence how your child grows. Why we review it each time is to talk about threats to your baby's or child's health and ways that you can take great opportunity to make changes.

How to Follow the Grid:

When you're looking at a growth grid, what you want to focus on is how your child is changing. One static point on the growth grid isn't as relevant as 5 data points over time. You want to know rates at which your baby or child is growing and the rate compared with the grid.

As you follow the grid along from infancy into toddlerhood, you'll notice that each time it will rise. Each data point at each set of time will increase. We care about the rate at which your baby or child grows, not the number.

Why You Shouldn't Focus on the Number:

Parents often come in to the office and say, "What percent is she at?" She might be at the 13th percentile; that might be phenomenal based on where she's been previously, or it might be concerning. Don't focus on the number. Have your pediatrician, family doctor, or nurse practitioner help you understand what the trends are for your baby's growth.

Parents, pediatricians, and nurses have been using growth charts since the late 1970s to track growth in infants and children. The charts were revised back in 2000 as data for the first charts (from a small study in Ohio) didn't accurately reflect the cultural and ethnic diversity of our communities.

The Hallmark of the Well-Child Check:

The hallmark of a well-child check is the review of a child's growth. Growth can be a reflection of a child's overall health, nutrition, or tolerance of possible underlying medical conditions. So understanding what your doctor or nurse practitioner says about your child's growth should be a priority.

If your doctor doesn't have a computer in the examination room, ask to see the chart on paper or on a computer in the office. It will not only inform you, I suspect it will delight you to see what your child has done since the last time he was seen. The human body really is a fine-tuned machine, and growth is simply astounding if you really stop to think of it. It's true your baby will at least double his weight by 6 months and triple it by about 1 year of age.

If You Have Questions:

If you have a challenge understanding how your child is growing or how the growth chart is presented, demand clarification. It's OK if you don't understand the presentation of facts on these grids; have confidence to speak up and ask the doctor or nurse practitioner to explain it.

Additional Information from

Wendy Sue Swanson, MD, MBE, FAAP
Last Updated
Mama Doc Medicine: Finding Calm and Confidence in Parenting, Child Health, and Work-Life Balance (Copyright © 2014 Wendy Sue Swanson)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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