Understanding Growth Charts

understanding growth charts for babies and toddlers

It’s pretty well known that one of the best ways to tell if a child (especially a baby/toddler) is healthy is if they’re growing well. It’s often the first question I ask about when assessing my own clients, and is something our moms, MIL’s, and grandma’s typically fuss about:

“Are they gaining weight?” 

“Growing well?” 

“Eat more so you can grow!”

To be honest, knowing our baby is gaining weight and is growing taller is a comforting sign to all of us that the body has what it needs to function and develop. But how do you know if your baby or toddler is growing well, too much, or too little? Well – we use growth charts – which you’ve likely seen your doctor plotting away on at your child’s regular check ups. While it looks super fancy and technical, it’s really not that hard to interpret if you know how it works, and what you’re looking for. While we usually leave the interpretation to the doctor, it always helps for us parents to really understand what it means when they give us status updates on their growth – because without understanding it – we may end up getting anxious over nothing, or complacent about a real issue. 

So without further ado, here’s all you need to know about understanding growth charts!

What are growth charts and how do they work?

Growth charts are graphs used by the medical community to keep track of your child’s growth pattern. Your child’s weight and height are plotted on a chart over time, and the rate of growth is compared to the rate of growth of a reference population of the same age and sex. Each chart has these “percentile lines” that run through it (5%, 10%, 50%, 90%, for example), which tells you which percentile your child falls on.

If your child falls along the 50th percentile, that means that half the reference population of kids of that age/sex are bigger than them, while half are smaller than them. If your child is on the 10th percentile, then 90% of the reference population is bigger than them, and 10% are smaller. You get the point.

Now, there are two types of growth charts – one created by the CDC (Center for Disease Control) and one by WHO (World Health Organization). In Canada, the WHO growth charts for Canada is used for all kids under 19 years of age, while in the US, the WHO growth charts are used more so for those 2 years old and under, while the CDC growth chart is for 2 years old and over. The main difference between the two is the WHO growth charts describe the growth of healthy children in optimal conditions (and who were exclusively breastfed for at least 4 – 12 months), while the CDC growth charts describe how certain children grew in a specific environment. Generally speaking, we’d want to use a chart that looks at the development of children under optimal conditions (WHO) as a standard for healthy children.

What percentile should your child be on…and when should you worry?

Growth percentiles on their own don’t tell you whether your child is healthy or not. They don’t necessarily tell you whether your child is overweight, underweight, or stunted in growth. What they do is compare your child’s growth to other kids of the same age and sex. That’s it. 

Many parents feel relief if their child is on the 50th percentile, but may freak out if they’re on the 90th or 5th percentiles. It’s not uncommon for me to get messages and emails from parents who’s doctors have rang an alarm for a child who’s on either end of the growth chart (top 10% or bottom 10%), and have been quick to claim that their child is falling off or at risk for obesity. This in turn causes parents to stress and push or restrict food on their child, which actually leads to more issues around food, and more often than not, the opposite effect on weight than what we want – not to mention, many psychological issues in the long run.

Growth Chart % - image of graphs and explanations

So here’s the kicker – it’s not what percentile your child is on that we care about… it’s about whether your child has a normal rate of growth over time – that is – they generally follow along the same percentile (or growth curve) over time. We want to see a fairly steady rate of growth vs. sudden swings in percentiles. Generally speaking, if your child drops or increases two or more percentile lines on the growth chart, we start to investigate why, as this is where there may be a cause for concern. This is what’s often referred to as “falling off the growth curve”. So being on the 50th percentile isn’t a good thing if they’ve just dropped from the 75th percentile. Being on the 5th percentile isn’t a bad thing if they’ve always been there. Every single child has a different body, genetic potential, environmental circumstance, etc. that puts them on a different trajectory. Not one is better than the other. It’s more about any deviation from your child’s norm that’s concerning. Always remember that.

What determines optimal health and genetic potential for height and weight?

Your child’s height and weight will generally change according to a pattern that is right for them. During the first few years of life, it can be normal to see some bouncing upward or downward from the previous percentile as they adjust and normalize themselves toward their genetic potential. However, as you learned above, a really large deviation in a short period of time can be cause for concern. So, how do you know if your child’s bouncing around on the growth chart is normal or not? 

Let’s first review the predictors of growth, and what factors affect the percentile that your child might sit on:
  • Birth weight and birth length are good predictors of your child’s genetic potential for weight and height (however, sometimes factors such as malnutrition during pregnancy, smoking, gestational diabetes, or other factors can affect this)
  • Feeding methods (breastfed babies typically grow faster in the first 6 months of life compared to formula fed babies. Formula fed babies tend to grow faster than breastfed babies after the first 6 months of life).
  • There can be some “catch up” or “catch down” periods where babies born smaller or larger than their genetic potential will adjust and regulate.
  • Some kids show what we call “constitutional growth delay”, where they start dropping percentile on the growth chart for the first three years of life, after which it stabilizes just under their growth curve until they hit puberty. Puberty can sometimes be delayed, though growth spurts at this time may result in achieving full genetic potential again. This is considered to be a normal growth pattern, though much more rare.
Circumstances you can expect to cause deviations from their norm include:
  • Not enough calories, too many calories, and the wrong type of calories are probably the most common thing that affects growth. Many kids, toddlers especially, enter a period of time where they’re increasingly demanding, distracted, and may develop “bad” habits around mealtime and lack structure in the environment to promote eating enough for their bodies. Others have issues with food and texture aversions, picky eating, and problems with stress at the table. Some eat too little as a result, and some may eat too much. Most of it has less to do with the toddler’s ability to regulate their appetite, and a whole lot more to do with the parent-child feeding relationship. Y’all may or may not know – but I’ve got my Feeding Toddlers course to help you prevent or tackle that! If ever there was a course you could do at home that was detailed and encompasses all the issues of feeding in toddlerhood- this is it! 

In kids who don’t get enough calories, you’ll often see that they’re weight will be affected first, and then later their height. You might also have a child that eats enough calories per day, but the quality of their diet is so poor and is missing enough growth-positive nutrients, like: iron, zinc, vitamin D, calcium, and amino acids. The biggest issue I see in my practice is kids who aren’t getting enough iron (which is more common in kids who eat heavy dairy based diets by the way). When I see a child with stunted height, iron is often the first thing I look at! I always recommend Healthy Height – a shake mix that contains all the growth boosting vitamins, minerals, protein, and amino acids that kids need for optimal growth – especially for kids who are underweight, have stunted height growth, are extremely picky, or who need extra amounts of protein in their diet for whatever reason. The shake mixes are delicious and have been clinically proven to help kids grow. And if you use code EATER15 you’ll get 15% off your first order! Please note that it is for children between the ages of 3 and 9 years old.

  • Chronic disease like long term or recurring infections, low immunity, inflammatory bowel disease (IBS), or celiac disease can cause decreased intake of calories without necessarily experiencing any gut issues or symptoms. I also seriously suspect malabsorption issues when a child isn’t growing the way they should despite eating enough calories (think Crohn’s disease or celiac disease).
  • Endocrine issues, which would be any abnormalities in hormone function (like thyroid, growth factor, insulin, and other hormones) can also affect a child’s weight and height.

The good news to all this? If an underlying reason for growth abnormalities is caught and treated early, growth patterns can be restored to where their genetic potential is!

Take away messages

  • No matter where your child is normally on the growth chart, they are at the right percentile for them. It’s no better to be at the 50th percentile than it is to be at the 99th or the 5th. 
  • The most important thing is whether your child is generally staying on their established growth curve.
  • Growth charts are not intended to be used as a sole means of diagnosing an issue. Instead, they contribute to an overall picture of your child’s health, so it’s wise to consider other signs and symptoms that show they are or aren’t making developmental progress.
  • No one’s growth and development is always perfectly smooth – there may be natural ups and downs on the growth chart based on illness, appetites, growth spurts, puberty, brief feeding strikes, etc.
  • Kids have an innate ability to know what they need to eat at different points in their life, assuming there’s no underlying medical issues. 
  • There may only potentially be a problem when there’s a downward or upwards jump on the growth charts of two percentiles or more, usually lasting many months.
  • Finding out the underlying cause of a true growth delay, or jump, is important and treatment should begin sooner rather than later.

Wanting help feeding your baby or toddler? I’ve got courses for you!

For babies 6-12 months of age who are starting solids or transitioning onto finger foods – The Baby Led Feeding course is for you!

For toddlers and older kids aged 1-8 years old that you want to teach to eat happily (no pickiness, mealtime battles, stress, and to have a healthy relationship with food) and healthily (eating all the right things at the right times) – the Feeding Toddlers online course is for you!

Enjoy your week!

*Please note that I do receive a small commission from any products purchased from the links in this post. But, this comes to no additional cost to you, and I will only ever link items that I FULLY support and stand behind! These small commissions help me keep my website alive and kicking so I can continue to provide you with valuable feeding info. 


meet edwena

Registered pediatric dietitian, mom of two picky-turned-adventurous eater, and the creator of the Texture Timeline™ – an exclusive tool to help move your baby through easy to more advanced purees and finger foods to prevent picky eating.

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