March 16, 2013

Weighing in on children's growth charts


---- — Parents have been reaching new heights with their questions about children’s growth curves and charts.

During your child’s routine examination with their doctor, probably the most important pieces of information gathered are height, weight and head circumference (if under age 3). The figures measure the growth of their body and brain (and, in turn, their overall health) and determine your child’s body mass index. These numbers not only tell you if your child is growing well, but can be the earliest sign that there is a problem affecting their overall growth and health.

We realize that all children are unique and grow at different rates into different shapes and sizes, yet parents often want to know how their child’s growth is doing compared to other children of the same age and gender. That’s where growth charts and growth curves come in. 

Growth charts contain multiple curves of growth based on data obtained from thousands of children to determine how your child compares to others over time. These curves are labeled from the fifth to 95th percentile. For example, if the child’s weight plots onto the middle curve of a growth chart, that would be the 50th percentile curve, meaning 50 percent of children weigh more than your child, and 50 percent weigh less. The higher the percentile number, the bigger a child compared to other children of same age and gender. Is there an ideal percentile? No, not really, as long as your child stays on the same curve over a prolonged period of time. If your child is in the fifth percentile for height and weight and has been staying on that curve for years, we don’t tend to worry very much. He’s just smaller than average, and odds are you or his other parent are, too.

So, when do we worry? We worry if your child starts crossing growth curves too quickly over time, with too much weight or height being gained, suggesting your child could possibly become overweight or obese. We also worry when points on a growth curve do not increase with age but stay constant or even fall off. This suggests an underlying problem affecting growth due to an inherited problem or an environmental stressor, such as poor nutrition or lack of physical activity. Both of these factors require further medical investigation by your child’s doctor.

What do I recommend? The next time you visit your child’s doctor, ask to look at the growth charts, and see if your child is staying on the appropriate curve for their size and ask what it means if they are not. If you’re not good at reading graphs, don’t worry. Your child’s health-care provider would be happy to teach you how to interpret the measurements. Better yet, they are always prepared to tell you what your child’s growth curve shows.

Hopefully, this tip will provide you and your child with a better understanding of what growth charts are all about.

Dr. Lewis First is chief of Pediatrics at Vermont Children’s Hospital at Fletcher Allen Health Care and chair of the Department of Pediatrics at the University of Vermont College of Medicine.