Picture this: In the same pediatrician’s office, two little boys happen to have their 3-year-old well visit on the same day.
Both start with a nurse, who weighs them and measures their height. Then they go to an exam room, and their provider shows each of the boys’ parents a growth chart.
The first boy is above the 90th percentile for both height and weight, which means he is bigger than 9 out of 10 boys his age.
The second boy is below the 10th percentile for height and weight, so he’s smaller than 90 percent of the boys his age.
Even so, the doctor tells both boys’ parents the same news: Each child is healthy and growing as expected.
“We don’t expect all kids to be the same size,” says UNC Health pediatrician Heather Williams, MD. “All we’re looking for is that each child is generally following their curve.”
Growth charts help parents and pediatricians see how a child is growing, an important marker of health. Dr. Williams and UNC Health pediatrician Edward Pickens, MD, explain what parents need to know.
How to Read a Growth Chart
Growth charts are graphs that compare a child’s weight, height and age, displayed on curves that represent percentiles, 5th through 95th. Your provider maps your child’s measurements as a plot point on that curve: height, weight and body mass index. Before age 2, head circumference is also recorded.
Your pediatrician’s office may use charts from the Centers for Disease Control and Prevention, which is a comparison with other American children, or the World Health Organization, which includes data from children worldwide.
“It tells you where your child is compared with everybody else, but that doesn’t mean you expect everyone to be on the same curve on the growth chart,” Dr. Pickens says. “I’m looking to see that they’re growing consistently.”
If your child is 18th percentile for height when they’re 7, their provider will expect them somewhere between the 10th and 25th percentile lines when they come back at age 8.
“It gives us a good indicator of whether kids are getting the nutrition they need, meaning calories but also vitamins and minerals,” Dr. Williams says. “Healthy growth and healthy weight gain is important for brain development, too.”
Why Children Grow the Way They Do
When it comes to the eventual size of your children, look no further than yourself and your child’s other parent (or, if your child is adopted, the biological parents). Genetics are responsible for about 75 percent of our eventual height and weight, with nutrition making up the rest, Dr. Pickens says.
So if your mom is 5 feet, 10 inches tall and your dad is 6 feet, 4 inches tall, you’re probably not going to have trouble reaching high shelves. If your parents are naturally lean, you probably will be, too. Of course, we all know people who are exceptions to these rules, but it’s a good start for making predictions.
Beyond genetics, it’s about calories. The more calories a child consumes, the taller and heavier they will be, Dr. Pickens says.
One important note: While today’s adults are often taller than their parents, don’t expect that trend to continue, he says. If you’re a typical American parent in your 30s, 40s or 50s, your parents and grandparents likely did not eat as many calories growing up as you did. Your children, however, probably eat a similar amount as you did. That’s why experts don’t expect future generations to keep growing taller and taller, Dr. Pickens says.
For parents who want to know how tall their children are likely to be, providers can perform a calculation called mid-parental height. For example: A girl whose mother is 5 feet, 3 inches tall and father is 5 feet, 9 inches tall is likely to be around 5 feet, 3 ½ inches tall, and almost certainly will end up between 5 feet and 5 feet, 7 inches.
Growth Problems in Children
Sometimes a child’s growth chart reveals an issue. A child whose height dips from the 50th percentile down to the 2nd or 3rd percentile might not be getting all the nutrients they need.
That’s a reason for concern, but it often can be fixed with simple changes in diet, such as adding healthy fats, Dr. Williams says. With enough avocados, cheese and full-fat yogurt, your child’s spot on the curve could be back to normal by the next checkup.
Sometimes unexpected growth chart results require further testing, through blood work, imaging or a referral to a specialist. For example: It’s normal for height to increase quickly during puberty, but an 8-year-old boy whose height has shot up beyond expectations might be showing signs of early puberty and could benefit from seeing an endocrinologist, a specialist in hormones.
A baby whose head circumference increases rapidly will need to be checked for hydrocephalus, a buildup of fluid in the brain that requires treatment. If your child is eating plenty of food but not gaining weight, your pediatrician may draw their blood to rule out celiac disease.
Children with chronic conditions, such as type 1 diabetes, and those facing major stress such as poverty or violence may not grow as expected.
If your pediatrician has concerns about your child’s growth, they will ask you questions about your family medical history and perform a physical exam of your child, looking for any skin or hair changes. They will want to know about what your child’s diet is like, what eating is like for them and if they have any restrictions or aversions around food.
Most of the time, a big number or a small number is not a problem to be solved, Dr. Williams says. “I tell them, ‘This looks like a healthy growth chart; I’m not worried. There’s nothing we need to be doing differently here.’”
Advice for Parents on Growth Charts
Growth charts can be fun and interesting, but it’s important not to get too caught up in them, the pediatricians say.
A small child is not less nourished than a larger child. They’re just different, and that’s OK, Dr. Pickens says. The goal is not to score “high” or right at 50 percent, but rather to follow the curve.
It’s also important not to put our society’s preference for tallness and thinness on our children.
“Some parents treat this as their first competition for their child, and we need to discourage that,” Dr. Pickens says. “We don’t want this to be the start of a complex for the child.”
Too much focus on size, rather than health, can lead to eating disorders and low self-esteem, he says. “We want children to feel healthy and comfortable in their skin, and to know that they’re the right size for them.”
Questions about your child’s health? Talk to their doctor or find one near you.