According to this article published recently in Wall Street Journal, 65% of parents are concerned about their child’s growth based on growth chart percentiles. At the same time, according to another study, only 53% of them can explain what a percentile is and even fewer can interpret the charts correctly.

Here are a few questions I hear from my patients who are confused by their children’s percentiles:

1. How important is my child’s percentile on the growth chart?

According to CDC website, ” Growth charts are not intended to be used as a sole diagnostic instrument. Instead, growth charts are tools that contribute to forming an overall clinical impression for the child being measured”. Your child’s growth should be assesses by your doctor in the context of many other factors, such as previous growth and feeding history, family history, past and current health conditions and many others. In other words, just the number on the chart is not a reason to be worried.

2. If the growth charts are based on the average weight and height of children in the US, does it mean that children who are in the 50th percentile are overweight, since we are in the midst of the obesity epidemics in this country?

Doctors use CDC growth charts for children 2 years of age and older. These charts are based on the size distribution in the 1960s, 1970s and 1980s. They are not likely to reflect the current obesity epidemics in children. Moreover, it seems like CDC is not in a rush to adjust the growth charts in order not to “normalize” the new, higher weights typical for children now.

3. My child is in the 5th percentile of her growth chart. Should I be worried?

Sudden changes in percentiles are more of a concern than the number itself. Your doctor may be using a phrase “following the curve” which means that your child is consistently within the same range on the chart. If your child has always been low or high on the growth charts, this could be her natural size, especially if the parents are petite or big. If, however, your child’s weight dropped suddenly or her growth slowed down significantly, your doctor should discuss it with you to rule out potential illness or developmental problem. The same goes for a sudden increase in weight or height.

4. My breasfed baby is very low on CDC growth charts. Should I start supplementing his diet with formula?

CDC and American Academy of Pediatrics recommends using WHO (World Health Organization) growth chart for children younger than 2 years of age. The reason for this is that the CDC charts for babies and toddlers are based on measurements of formula-fed babies in the US who grow faster and tend to be larger in general. The WHO growth charts, on the other hand, are based on the size distribution of breast-fed babies from 6 countries. According to CDC website, “The WHO standards provide a better description of physiological growth in infancy”, so if your doctor is using a CDC chart, the percentage might be not accurately describing your baby’s growth, especially if you are breastfeeding.

Do you have any questions or concerns about your child’s percentiles? Please comment below.