As parents, we are wired to take care of our kids making sure that they are healthy, safe and growing well.  And each of these areas can bring quite a lot of worry and anxiety into our lives. 

When it comes to growth, It seems easier nowadays than ever to ensure that the child is growing well and thriving because we are lucky to have growth charts. But, unfortunately, it also means that the growth chart curve can come back haunting some of us in the night. 

Sometimes, there is a valid reason for concern and in other cases, it’s triggered by common myths about what is a healthy growth pattern. And this is exactly what I would like to tackle in this blog post. 

What are growth charts?

In the US and UK doctors and dietitians use two sets of growth charts. One set is for babies and children under 2 years of age. It includes growth charts for length, weight and head circumference. The second one is for older children 2 to 18 or 19 years and it includes growth charts for height, weight a BMI (Body Mass Index Calculator) or height-for-age and weight-for-age.

Growth charts differ slightly between the countries but I will not go into a lot of detail about this. Maybe something to consider for a different post?

Growth charts used to be kept behind the closed doors in doctors’ offices and rarely made their way into the discussion at regular visits but now things have changed. Doctors now routinely discuss the growth chart measurements with families and ofter show them the chart to explain the growth pattern.

The primary purpose for using growth is to compare a child’s growth to a typical growth pattern of children of the same age and sex. 

There are growth charts for children with certain medical conditions, but, for the purpose of this post, we will look only growth charts for healthy typically developing children.

What are the growth chart lines?

To create growth charts, many healthy children of both genders and different ages are measured in a specific country at a particular time. On the basis of their growth, centiles (the curved lines you see on growth charts), are created. Each line or centile marks the height and weight below which a certain number of children of a particular age and gender fall.

For example, if you hear your doctor saying that the child is “15 percent for height”, it means that the child is taller than 15% of children of the same age.  Or “85 percent for weight” means that the child is heavier than 85% of kids of the same age.

And here are the main myths about growth charts I see in my practice as a dietitian and child nutritionist.

How to read a child growth chart - girl in a red cape measuring her height

Myth #1: 50th percentile is “the golden standard” of growth

The results of a national online survey among parents in the US showed that many associate a higher percentile with better growth. Being lower than 50th and even 90th percentile is often considered a sign of a growth problem.

Reality: 

There is nothing magical about being on a specific percentile. In fact, although the 50th percentile is a thicker line on the US growth charts, it has been de-emphasized recently on the growth charts used in the UK, so that it is easier for clinicians to explain the growth chart results to parents.

Here is what being on the 50th percentile truly means: the child’s measurements are higher than 50% of the kids of the same age and gender and lower than measurements of 50% of the kids of the same age and gender. 

Myth #2: A slight downward movement in percentiles is a sign of poor growth.

Reality: 

The child’s measurements need to suddenly cross at least 2 centile lines whether upwards or downwards, in order to be considered a reason for concern and require an investigation into a child’s growth and nutritional status. If the child’s growth curve is predictable and consistently stays within the same percentile gap, the child is growing well.

Myth #3: If the child’s growth curve is too high or too low on the growth chart, it is an automatic reason for concern.

Reality:

Healthy children come in all shapes and sizes. As far as the child’s measurements are within the growth chart’s extreme points (5th and 95th percentiles on the US growth charts and 0.4th and 99.6th percentiles on the UK growth charts) and the growth curve is steady and consistent, the child is growing into the body that is healthy for them.

As dietitians, we are trained to look at the parents’ height and build before interpreting the growth chart measurements. In the UK, we even have a nifty tool called “Parent Height Comparator”, included in the growth chart set. It allows seeing how the child’s height measurement compares to that of his both parents to ensure the child is following the genetic pattern of growth.

If the measurement appears to be outside the weight growth chart, the next step for clinicians will be to calculate a child’s BMI (only for kids 2+) and see if there is a true reason for worry. Sometimes, even if a child seems very low or too high on a weight and height growth charts, his BMI is within the normal range and the child is growing well. 

Myth #4: A single measurement on a growth chart that appears too high or too low is a reason for concern.

Reality:

A single measurement cannot reflect the true picture of growth. It is always helpful to track earlier measurements and use them to create a growth curve. 

For example, if your child is only 5% for weight and 15% for height on their growth charts it may sound like he is too skinny and not growing well, but, if we look at their growth curve, we often see that their growth has been consistently close to those centile lines. And this means that the child’s growth and weight gain are just fine, even if a single measurement appears too low.

Still confused and worried about your child’s growth? Make sure to talk to your doctor or dietitian to help you interpret the percentiles and develop an action plan, if needed.

Can you add any other growth chart misconceptions to this list?

How to read a child growth chart - boy in a blue shirt and jeans measuring his height

More articles to help you get the right nutrition for your child:

COMPLETE GUIDE: How often do kids (0 to 5) need to eat? Sample schedules included.

Top 6 nutrients for children and their food sources

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