What does this tool measure?

This tool uses your child's weight and height to compare your child's size to that of other boys or girls of the same age. Not all children are the same. Some are naturally larger and some are naturally smaller. Your child's size will be given two numbers—a BMI value and its percentile. The percentile is the number that ranks your child's size among other children of the same gender and age.

What's most important is that your child is at the same percentile over time, so it takes several measurements to assess your child's growth. You should talk with your doctor if your child suddenly shifts up or down in percentile. A gradual change from one percentile to another is probably not a cause for concern.

Talk with your doctor if you are concerned about your child's weight. Finding that a child is "overweight" or "underweight" is a medical diagnosis. Your doctor can give you steps to take to help your child reach and stay at a healthy weight.

What do the results mean?

If your child is on the very low end of the percentile scale (for example, the 3rd percentile), you may be concerned that your child is too small. If this is the case, talk to your doctor. It may be that your child has always been small and that this is the normal growth pattern for him or her. Your doctor can check your child to make sure that he or she is growing normally.

Often parents of very small children push their children to eat more because they are concerned about their growth. This can cause problems. The child may resist the pressure to eat and will not gain weight as well as he or she should. Pressuring children to eat usually causes them to eat less, not more. Talk about your child's weight with your doctor. As long as your child is growing normally, you can relax a little about feeding him or her.

If your child is on the upper end of the percentile scale (for example, the 95th percentile), you may be concerned that your child is too big. If this is the case, talk to your doctor. It may be that your child has always been large and that this is the normal growth pattern for him or her. Your doctor can check your child to make sure that he or she is growing normally.

Parents of larger children are sometimes tempted to restrict what their children eat, to keep them from gaining too much weight. This doesn't work. When a child doesn't get enough to eat because food has been restricted, he or she learns to overeat when the chance arises. These children end up gaining more weight, because they become anxious about food and eat more when they get the chance. Again, it is good to discuss your child's weight with a doctor who can help you see if your child's growth is within his or her normal pattern.

Your child's weight over time is the most important thing to think about when you are concerned about what your child's weight should be at any age. Your child's doctor will decide what your child's weight should be, based on what your child's weight has been over time.

What's next?

If you are concerned about your child's weight, or if your child has had a large change in BMI (whether up or down), talk to your doctor. Remember that BMI-for-age is just a guide.

If your child does have a weight problem, you and your doctor can talk about what you can do to help, such as providing healthy foods and helping your child to be more active.

Source: Centers for Disease Control and Prevention (2011). Healthy weight—It’s not a diet, it’s a lifestyle! About BMI for children and teens. Available online: http://www.cdc.gov/healthyweight/assessing/bmi/childrens_bmi/about_childrens_bmi.html.

For more information, see these topics:

• Growth and Development, Ages 2 to 5 Years
• Growth and Development, Ages 6 to 10 Years
• Growth and Development, Ages 11 to 14 Years
• Growth and Development, Ages 15 to 18 Years
• Healthy Eating for Children