Childhood growth: What does the growth chart mean?

Chances are, when you take your child in for his or her well-child check up, the growth chart and growth percentiles may be mentioned.  But what’s that really mean?

I recall that when my kids were babies, it seemed most parents were reporting their child’s percentiles to the world. It seemed like the bigger the percentile number the prouder the parent.

As a dietitian and as a parent of two kids who lived at the lower growth chart percentiles, I did not share much, but I did feel like saying “This is not a competition!”

What do percentiles mean?

The term percentile indicates where a child ranks when compared to others in size. For example, if your 5 year old is at the 25th percentile for height, that means 25% of measured 5 year olds are shorter than your child, and 75% are taller than your child. Many times our experience with percentiles are in a standardized test, like the ACT, where the higher the percentile the better, but that is not the case with growth. A standardized academic test uses one point of reference to grade the child, but when evaluating a child’s growth it is best to use multiple points. Multiple measurements over a period of several years allow a trend to be noticed.


one plot on the growth chart.png
Established Growth curves.png
Growth concerns.png

What is BMI?

Body Mass Index (BMI) has become a screening tool frequently used in health care to determine someone’s health risks. BMI is not measured in children until they are greater than 2 years of age. For adults at maximum height, the BMI is evaluated based on the exact number, but for children it is evaluated based on percentiles that are plotted on a growth chart (as shown in the above graphics). Typically, a child may be considered overweight with a BMI greater than the 85th% tile, and obese if the BMI is greater than the 95th% tile. But adults are considered to be overweight if their BMI is greater than 25.

The BMI is calculated as follows:

Weight (in kg)/height (in meters2) = BMI

Use BMI with caution?

Recently, many health care providers have raised concern about the overuse of BMI as a health indicator. The value for BMI does not measure the amount of body fat vs muscle. It can be a very inaccurate measurement for an athlete that is heavily muscled. The BMI can also be a poor indicator of nutrition status in children that have a muscular disease, like cerebral palsy.

Most importantly, the BMI is a screening tool. A high or a low BMI does not necessarily mean that there is a concern. Therefore, it would be best, if a pediatrician along with a registered dietitian review the health information for a child to determine if there is a concern.

For children younger than 2 years the World Health Organization (WHO) Growth Chart is used. The reason for this is because the WHO growth chart was compiled using data on mostly breastfed infants from developed countries, therefore, it is thought to be more representative of children at that age.

Evaluating the growth of a child with special health care needs.

The general recommendation by multiple medical organizations is to track a child’s growth on either the WHO growth chart for 0-2 years of age, or the CDC growth chart for ages 2-20.  If a child has special health care needs, it’s still recommended to track them on the standard growth charts, but keep in mind that the growth of a child with special needs can deviate from the norm, therefore, the growth trend for that particular child needs to be identified. There are multiple growth charts available for children with special needs, but many of them are based on small sample sizes. The special needs growth charts can be used along with the standard growth charts for reference.

It is difficult to obtain height measurements in children who are unable to stand. This is why BMI is not always the best indicator of nutrition status in some children with special needs. A qualified pediatric dietitian can perform a nutrition focused physical assessment (NFPE) on a child with special needs. An NFPE can reveal changes in skin, nails, hair, muscle, and fat stores if done by a consistent person. The NFPE can be used along with, weight and height measurements in children with special health care needs to determine nutrition status.

Size is not the only measure of health.

There are many factors other than size that indicate health. For children, we want to see that a child is consistently maintaining a growth curve, but it is also important to assess their energy level, sleeping habits, eating habits, and mental health.

Good nutrition will help your child reach their genetic growth potential, whether that is barely over 5 feet tall or well above 6 feet.

So, the next time you are at a play group or with other parents, and you start to hear bragging about their child’s percentile, maybe you will have the confidence to say “This is not a competition!”

If you have concerns or questions about your child’s growth shoot me an email. I answer all questions sent to me.