Wondering Why Your Child's Height or Weight Isn't 'Average'?

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If you’ve obsessed over your child’s place on the growth chart at the pediatrician’s office, we hardly blame you. From the moment she entered the world until the day she heads off for college, her height, weight, and body mass index (BMI) will be dutifully recorded and tracked.


These aren’t just numbers for you to swap during playdates -- they’re also a snapshot of your kid’s growth, development, and nutrition, explains Michael McKenna, MD, a pediatrician at Riley Hospital for Children at Indiana University Health. A consistent, gentle upward trajectory on the growth chart is an indicator that your child is eating right and developing well -- which basically feels like the parenting stamp of approval.

But should you be worried if your toddler or preschooler is persistently on the higher or lower end of weight and/or height? Not necessarily.

These are some common reasons your child may not be within the average percentiles for weight and height -- some are problematic but others are perfectly fine:


Wondering why your kid is always the shortest one in his class? Take a look in the mirror. If you and your partner are on the short side, your child is likely destined to be as well. As long as he’s within the mid-parental height range -- an estimate your pediatrician makes using both biological parents’ height -- there’s no reason for concern, McKenna says.

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However, if your child remains stubbornly below that range, or experiences a drop-off in growth, your pediatrician may refer him to an endocrinologist for further evaluation.

Genetics can also play a role when it comes to underweight children. “If your child is below the 10th percentile for weight, it is quite possible that they are just genetically inclined to be that low, especially if the parents are also on the thin side,” McKenna explains. In this case, instead of fretting over the number on the scale, focus on making sure your kid is eating a healthy diet.

Eating Habits

If your child’s weight stays below the 10th percentile -- and genetics aren’t an underlying cause -- consider her eating environment and whether she’s eating enough. Does your family have meals while the TV is on? Is your kid a grazer who never sits down to eat an actual meal? Is she drinking too much juice or water?

“All of these things, and more, can lead to problems with maintaining a proper caloric intake and maintaining weight,” McKenna says. Your child’s pediatrician can give you personalized advice on how to create a plan that helps your child get the nutrition she needs.

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Food Choices

On the flip side, if you can’t figure out why your preschooler won’t budge from the 90th percentile for weight, take a close look at what he’s eating. “Weight percentile is almost always related to caloric intake,” McKenna says. “The higher the caloric intake, the higher the child's weight and the more likely they are going to be on a higher percentile.”

Numbers do matter here: If your child is above the 85th percentile for BMI, he or she is considered overweight. If your child is above the 95th percentile, he or she is considered obese. Sounds serious? It is.

“Multiple studies are now showing that overweight and obese children become overweight and obese adults,” McKenna cautions. “Kids don't just ‘grow out of it.’ It is not ‘just baby fat.’”

To help get your kid back on track, McKenna recommends taking a hard look at your family’s dietary habits and food choices, and making strategies to improve them. You can also discuss changes in lifestyle and eating habits with your health care provider, and work together on ways to implement them.

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Medical Issues

Genetic disposition is the biggest reason for a child to be consistently underweight, but sometimes, an out-of-nowhere dip on the growth chart can be the first indicator that something is wrong. For example, “if you notice a sudden drop in weight,” McKenna says, “there [is] a wide variety of diseases to think about: problems with the intestinal tract leading to difficulty absorbing nutrients or situations where the body is burning up too many calories.”

But don’t panic at the first sign of low weight gain. “For most of these, there are also other signs and symptoms that go along with them,” he adds. “So rarely do any of these present themselves only as poor weight gain without things like fatigue, bloody stool, respiratory difficulties, fever, or other local and systemic findings.”

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In very rare cases, a hormonal issue could cause a child to grow inexplicably tall. “Typically, this is not really discovered until a child enters young adulthood and continues growing when they should stop growing,” McKenna says. But if you’re concerned that your toddler or preschooler is off-the-charts tall, it can’t hurt to talk it over with your pediatrician.

Bottom line? If you have any concerns about your child’s development, tell your child's doctor so you can work together on a solution, or so the doctor can help rule out any problems and ease your fears.


Bonnie Gibbs Vengrow is a New York City-based writer and editor who swapped her BlackBerry and MetroCard for playdates and PB&J sandwiches -- and the once-in-a-lifetime chance to watch her feisty, funny son grow up.

Photo via iStock.com/Choreograph

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