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The growth chart debate: ‘That is not how kids grow’

The pros and cons of using growth charts to track kids’ development
WATCH: For Canadian children, growth chart mapping is as routine as medical appointments and immunizations. But one doctor says they are an unreliable marker of health and just lead to stress. Laurel Gregory explains in this Family Matters.

In spite of all the spinach I feed him, there’s a good chance my son won’t be the next Pascal Siakam, a Toronto Raptor measuring in at 6′ 9″ tall.

Don’t get me wrong: I’m all for dreaming big. But I doubt my son will have the height required for a career in basketball.

How can I be so sure? Well, there’s the whole genetic thing  — I’m 5’2″ and his dad is 5’11” — and then there’s the growth chart results.

For nearly five years at check-ups, the public health nurse has pulled out the growth chart and confidently stated, “25th percentile for height.” In other words, the majority of kids my son’s age are taller than him. Bye-bye NBA.

Growth charts are a kind of childhood ritual. With each immunization, public health nurses document a baby’s head circumference, height and weight.

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Then, they plot the result on a chart, assessing where the child lands compared to other children their age.

According to Dr. Janice Heard of the Canadian Paediatric Society, the World Health Organization Growth Charts have been used by health professionals in Canada for decades.

“The WHO actually did a worldwide study using six different countries including Brazil, Norway, Oman, United States, Ghana and India. So a very diverse population and took millions — literally millions — of children and measured and weighed them and did head circumference, and then produced their growth charts. So their growth charts represent a much more diverse population as you can well imagine.”

Heard says the WHO specifically charted middle class children who were exclusively breastfed in their first few months.

She says the chart is a helpful tool for pediatricians. For example, if doctors see a spike in the child’s weight, it’s a signal that perhaps they have a thyroid issue, are eating too much or not exercising enough.

READ MORE: Canadian babies are heavier and taller than global standards. Here’s why

However, Dr. Aaron Carroll, a professor of pediatrics at Indiana University School of Medicine, and the voice behind YouTube’s Healthcare Triage, argues growth charts are not being used properly because they don’t reflect how children grow.

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“We actually looked at how often kids will change percentiles and it turns out most do. Those growth charts were not designed by following people over time and then creating lines. They just basically measure tons of kids at certain times and different ages and then used math to connect them,” Carroll said.

“So the kid at the 25th percentile for one age is not the same kid they measured at the 25th percentile at another.

“We just assume by making those lines that that’s how kids grow. That is not how kids grow. They grow fast, they grow slow. They grow fast, they grow slow.”

READ MORE: Do children need vitamin supplements? It may not be necessary

Carroll adds that parents are also misinformed about how they work, so they treat the chart results like a grade.

“I can’t believe how many parents are utterly obsessed with the growth chart. You know they come in and want to know what percentile they are, whether they’re gaining weight, grandparents are at home waiting to check if they’re good enough.

“The truth of the matter is they are way overestimating the importance of — both the growth chart and the actual number that they’re receiving.”

READ MORE: Why your child’s weight in grade 5 could predict future obesity risk

Heard admits the results can create anxiety but their ability to provide a “warning sign” to doctors is too valuable to dismiss. She says it’s up to doctors and nurses to educate parents about the charts in order to clear up misinformation and ease stress.

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A few months ago a grocery store cashier asked me the age of our second son, who was sitting in the front of my cart.

“Oh, he’s one. He just looks younger because he’s so small,” I replied, thinking back to our last appointment and our 10th percentile reading.

The cashier looked at me kindly and said that wasn’t his line of thinking at all. He told me about his kids, who were several years older and exerting their independence.

I gathered up my 10th-percentile baby and left to pick up my 25th-percentile four year old, realizing in the grand, growth chart of our lives — all of these numbers will be the least of my worries.

Laurel Gregory is the reporter and producer of Global News Family Matters.