Kid's growth charts: here's what you need to know

In my humble opinion, one of the most misunderstood pediatric assessment tools are your kid’s growth charts. All those lines, the percentiles, the different charts – what do they REALLY mean?

I think parents have a lot of questions about growth in general – not just the growth chart tool itself. Some of the questions I’ve recently been asked include:

  • “How can you really tell if my child is growing well?”
  • “Did I mess up their growth during the pandemic?”
  • “How do I get them to eat more/less to grow more/less?”
  • “What’s the best percentile to grow on?”

Understanding childhood growth can be tricky for a number of reasons.

First, let’s address the elephant in the room because diet culture has a massive influence on how parents and health care providers interpret “good” or “healthy” growth. (There’s lots more to unpack here. I’ll save that for another post).

There’s also the fact that the actual growth chart tool is often misinterpreted or misrepresented.

Health care professionals may label kids as “too big” or “too little” without cause. Subsequently, poor advice follows about how to fix their growth problem. If you combine a scary label with poor advice, it almost always results in an anxious parent. We tend not to parent well under stress and anxiety. Oftentimes without the proper advice or support, parents move away from a trust-based feeding model and opt for the “do whatever it takes” approach to remedy the growth problem. This results in a monumental shift in the feeding relationship between parent and child. The ripple effect is long lasting and extends into many (if not all) areas of a child’s life.

There are many amazing health care providers who do a fantastic job of tracking and interpreting growth patterns and providing excellent support. My training at a children’s hospital was second to none in this area! But I do need to acknowledge that not every family has had a great experience with their health care provider and their child’s growth charts.

What follows are some questions (and answers) to help provide more context and information regarding growth charts so you do not need to be fearful of this tool and know how to ask good questions about your child’s charts at their appointments.

Is tracking my child’s growth on a growth chart necessary? Isn’t tracking weight “diet culture?”

Monitoring a child’s growth is important. Really important. It’s one of the best ways to track the growth and development for kids and to pinpoint, at an early stage, potential nutritional or medical health issues. They’re often an early detection tool to flag if something is off.

Growth charts also help to paint a picture of your child’s own unique and healthy growth pattern for their body. This personal benchmark of sorts is incredibly helpful to have on hand at the doctor’s office, in case your child has growth concerns down the road.

However, growth charts are only one tool in a bigger toolkit that we use when determining if growth is going as expected or not. A growth chart should never be used in isolation to make decisions or provide recommendations. It should always accompany other questions and/or investigations.

When used correctly, growth charts do not contribute to the development of an eating disorder, body dissatisfaction or a poor relationship with food. I acknowledge though that some of you may have had an experience with a health care provider who did not use this tool correctly. Their comments may have triggered a train reaction of events that led to a poor relationship with food and/or disordered eating for your child. This is not the intent. I’m so sorry if this is/was your story.

Do growth charts show doctors/dietitians how good or bad I am at feeding my kids?

Growth charts are NOT a parenting report card.

Do not use them (or let others use them against you) as a yard stick by which to measure yourself or your child. There are SO many factors that influence how a child grows.

Should I track my child’s growth on a growth chart at home?

Unless you have been medically advised otherwise, you should not have a growth chart at home to plot your child’s growth. This can easily become obsessive and interfere with your feeding relationship with your child. Let an experienced health care provider do this for you and advise you on your child’s growth at well-child appointments.

How often do healthy children need to be weighed?  

In Canada, it is recommended that growth is measured:

  • At birth
  • Within 1-2 weeks of birth
  • Then at one, two, four, six, nine, 12, 18 and 24 months of age
  • Then once per year for kids over 2 years of age

Please note that the above recommendations are for a healthy child. Another reason why your child might need to step on the scale, aside from growth concerns, include having an accurate weight to dose a new medication. Most pediatric medicines are prescribed based on a child’s body size.

Remember that you and/or your child can refuse to have their weight taken if it’s not necessary for the purpose or reason of the visit. You can also request that discussions related to your child’s weight do not occur while your child is present.

Depending on your child’s growth and what’s been going on, your doctor may advise you to weigh your child at home between in-office visits. This has increased more now since the pandemic and a shift to tele-health medicine. If this is the case, remember that your scale at home will be very different than your doctor’s scale. It’s always best to compare “apples to apples”.  

A quick note about infant scales. There has been a big proliferation of infant scales on the market recently. I would advise against buying one, as frequent weighing of your baby can cause excessive worry and interfere with the feeding relationship and ultimately prevent responsive feeding.

For kids over 2 years of age, it’s not advised to weigh them more than once a year. I realize that with the pandemic, many well-child visits are not happening. If you decide to take their weight and height at home, please ask their permission first and do this in privacy, without an audience of other family members.

This might sound like: “Hey Ben. It’s your birthday. Would you like to see how much your body has grown in the past year?” Respect their decision. Avoid any judgmental statements (positive or negative) about their height/weight. Keep it all matter-of-fact. If you can’t keep it neutral or indifferent, then don’t measure or weigh them.

And if you have a scale at home, please keep it tucked away somewhere that it’s not accessible.

I’ve heard there are different growth charts. Which one(s) does my child need?

The WHO (World Health Organization) growth charts for Canada are the most commonly used in doctor’s offices for growth monitoring. (More here)

For kids 0-2 years, there are 3 different charts.

  • Weight and length chart
  • Weight-for-length chart
  • Head circumference chart

For kids 2-18 years, there are 2 different charts:

  • Weight and height chart
  • BMI (body mass index) chart

There are also different/separate charts for children with various cognitive, developmental, genetic or other disorders. Your doctor might monitor your child’s growth on a few different charts to compare.

Your health care provider will choose the right tools (charts) for the job. Want to know more about which charts they are using? Just ask!

What are these “percentile” lines that doctor’s talk about? Should my child track on the same percentile line for each and every growth chart?

The percentile lines you see on a growth chart are the compilation or average of millions of measurements of children’s growth. The percentiles describe a child’s growth relative to other children who are matched for age and sex. These percentiles are NOT intended to prescribe growth.

Your child won’t necessarily track on the same percentile line for height and weight and head circumference etc. It’s perfectly normal and okay for their weight percentile to be higher or lower than their height percentile.

Here are some examples of what the percentiles mean. I’ve kept height and weight at the same percentile for simplicity purposes of the examples but this is not expected. Healthy growth happens at many different combinations of various percentiles!

  • 50th percentile weight AND height: 50% of kids (same sex and age) will weigh more and measure taller than your child and 50% of kids will weigh less and measure shorter than your child. 
  • 3rd percentile for weight and height : 97% of kids (same sex and age) will weigh more and measure taller than your child and 3% of kids will weigh less and measure shorter than your child. 
  • 97th percentile for weight and height: 3% of kids (same sex and age) will weigh more and measure taller than your child and 97% of kids will weigh less and measure shorter than your child. 

What’s the ideal percentile? 

There is no “ideal” percentile.

What’s most important is that your child is growing fairly consistently. It doesn’t matter if growth is consistent on the 10th percentile or 85th percentile. We also don’t expect perfect tracking along a percentile. Variation slightly above or below a percentile line is normal!

Aren’t there percentiles that indicate that my child is “overweight” or “failure-to-thrive”?

Conventional approaches use absolute cut-off points when looking at growth percentiles. The cut-off point (be it for underweight or overweight) is often paired with advice to “calorically restrict the child to correct the problematic growth” or “do whatever it takes to get the child to eat”. This is not the approach we take in our practice.

We use the Satter Feeding Dynamics approach to compare your child to themselves. If weight increases or decreases abruptly (no matter what percentile your child is growing on) it’s worthy of further investigation. After medical causes of accelerated growth or weight faltering are ruled out, we look to support families to restore positive feeding practices in the home.

What causes a child to suddenly cross percentiles?

Growth divergence away from your child’s own unique normal pattern (above or below) can happen for MANY reasons! Too many reasons for us to discuss in this blog post. Here are a few of the big categories a doctor and/or dietitian would look at with some examples:  

  • Underlying medical causes:
    • Change in medication, undiagnosed condition, malabsorption
  • Nutritional causes
    • Not enough food, food with inadequate calorie content  
  • Developmental causes
    • Their personal needs are not being met, lack of stimulation
  • Psychosocial causes
    • Neglect, child abuse, emotional deprivation
  • Family Feeding Dynamics
    • Too much pressure, not following division of responsibility in feeding

What is the best thing I can do to make sure my kid grows well on their own natural percentile that nature intended for them?

If I had to summarize it in 3 points, it would be:

  1. Follow a trust-based and responsive feeding model
  2. Promote food neutrality in your home
  3. Engage in positive joyful movement together as a family

Sounds simple but sometimes it’s really hard to transition to a trust-based feeding model. That’s why we’re here! Reach out if you are looking for support to help navigate a concern that you have about your child’s growth.

My final plea! Call your family doctor or pediatrician or our team if your child’s growth concerns you. Put to rest any fears or anxieties that you have so you can focus on your jobs in feeding and let them do their job with eating (and growing!).