Whether you have a kiddo in a high weight percentile, or barely on the chart, you may have had at least one check up that stressed you out. To help, we’ll cover what growth chart percentiles really mean—and what they don’t.
Growth Chart Percentiles
From the CDC: “Growth charts consist of a series of percentile curves that illustrate the distribution of selected body measurements in children.” At each check up we have for our babies, and then for our kids as they continue to grow, we’ll be told where they are on the growth chart—but it’s all too easy to worry that a child in the, say, 24% is too small, and one in the 98% is too big.
More on that in a moment.
CDC Growth Chart for Girls and Boys
If you want to look at the base charts, here are a few links to pdfs if they help you.
- CDC’s growth chart for girls baby to 24 months.
- CDC growth chart for girls aged 2-20.
- CDC’s growth chart for boys baby to 24 months.
- CDC growth chart for boys aged 2-20.
How is a growth chart percentile calculated?
At a check up, the clinician will measure height, weight, and head circumference. That data will be plotted on the growth chart and compared to the normal range and to the child’s own previous curve. This is what you will typically be shown on a computer in the exam room.
What is a normal growth chart percentile?
Here’s a great explanation of “normal” from UPMC (emphasis is theirs):
It’s important to note that there is a wide range of what is considered normal. In fact any infant percentile can be considered normal, as long as a child continues to follow that growth percentile or above. If a child’s growth follows the curve of the chart, it indicates that they are getting the correct nutrition and their growth is progressing as expected.
If a child continues to drop in percentile on their child growth chart, this could be cause for concern. Dropping may indicate that they are not getting adequate nutrition or that further testing should be done to evaluate what may be impacting their growth.
TIP: That means that a child at 99% on the chart can be NORMAL. And a child at 2% on the chart can be NORMAL. And anywhere in between. It’s more about whether the child is on their own growth curve or if they’ve spiked up or down.
What can growth charts tell us about our kid’s health?
Charts can be helpful in highlighting potential issues to keep an eye on. If a child continues to drop in percentile on their own growth curve, that could be a cause for concern. If a child spikes up, that too could be cause for concern. If either happens to you, be sure to ask questions, request additional testing or information to be gathered—the chart alone may not be the best diagnostic tool.
TIP: As the CDC says in their own words, “Growth charts are not intended to be used as a sole diagnostic instrument. Instead, growth charts are tools that contribute to forming an overall clinical impression for the child being measured.”
What are they not great at telling us about our kid’s health?
Growth chart percentiles tell us nothing about a child’s body mass or lifestyle. They don’t share how active or sedentary a child may be, what he eats, drinks, or likes to do. They are a snapshot of three specific growth measurements and provide an incomplete picture of total health.
How does BMI play into this?
To calculate BMI, you’d take a child’s age, height, and weight and plug it into this calculator. The result will tell you whether a child is underweight, a healthy weight, overweight, or obese.
BMI-for-age percentile shows how your child’s weight compares to that of other children of the same age and sex. For example, a BMI-for-age percentile of 65 means that the child’s weight is greater than that of 65% of other children of the same age and sex.
It’s worth noting that these BMI percentiles express a child’s BMI relative to US kids who participated in national surveys conducted from 1963-65 and 1988-94. So not exactly their peers of today.
But again, REMEMBER that these figures don’t take the full picture into consideration. BMI doesn’t reflect a child’s body mass, nor does it consider lifestyle. Here, again, the CDC says that, “Please keep in mind that this BMI calculator is not meant to serve as a source of clinical guidance and is not intended to be a substitute for professional medical advice.”
What’s the difference between WHO and CDC growth charts?
And if you thought this wasn’t already complicated enough, the World Health Organization AND the CDC both have their own growth charts. The CDC actually recommends that clinicians use the WHO one for babies up to 24 months because the CDC growth charts are references and they identify how typical children in the US did grow during a specific time period. But remember: These “typical growth patterns” may not be ideal growth patterns for any given child.
The WHO growth charts, on the other hand, sets a standard and identifies how children should grow when provided “optimal conditions.” (I have yet to be able to find an explanation of exactly that that means so take it with a grain of salt!)
What should I do if our doctor is concerned about my child’s growth chart percentiles?
First, know that you don’t have to solve it or have a plan in place right at that very second. It’s okay to digest their concerns, and then ask questions—even if you need to call back a few days later or email them after you get home. You can ask for additional testing. Ask what will happen if you don’t do what they suggest. Ask for another consultation with a second doctor to see if they agree.
TIP: Just because a child is low on the growth curve does not mean that they need “fattening up”. If a health care provider says that, probe deeper.
For More on Growth Chart Percentages and BMI
You can listen to our latest Comfort Food podcast episode all about the topic. We share our own experiences with kids who have been at the top and the bottom of the growth curve and share more in depth on these topics.