Baby growth charts and how to use them

Growth monitoring is an essential part of a child’s health care, from birth through adolescence. Your child’s growth will be monitored on a growth curve at each check-up and their growth will be classified according to a certain percentile. Understanding percentile curves and how they are created will help you understand your child’s growth patterns.

While each child has their own set of genetic markers that make up a growth profile, sudden major changes or deviations from a typical growth curve percentile should be investigated, tracked, and treated if an underlying cause is found. Your health professional will determine when and how to intervene. 

Understanding growth curves                                                                                

Growth curves are the accepted manner in which to keep track of the evolution of height and weight. Most children will stay within their percentile profile growing at a predictable rate, creating a curve along with the growth chart. By comparing your baby’s measurements –length and weight– to those of other children the same age and sex, and to these same measurements from previous checkups, your child’s doctor can determine whether your baby is growing in a healthy way. 

What do percentiles mean? 

Percentiles are used to understand and interpret data, including test scores, health indicators, and other measurements. When it comes to your baby’s growth, percentile numbers indicate what proportion of a certain set is below that percentile number. 

For example, if your child’s weight and/or height is at the 60^th percentile line, that means that out of every hundred children of his age, 60 will be smaller than they are and 40 will be larger. Similarly, a child who is at the 90^th percentile of growth will be larger than 90% of other children and smaller than 10%.

Who determines the growth curves and percentiles?

Growth charts are made by official bodies, specifically, the World Health Organization (WHO) and the Center for Disease Control (CDC). Many professionals in the United States use the WHO’s growth chart to monitor infants ages 0 to 2 years of age, and the CDC growth chart to monitor children older than 2 years.

What happens when my baby’s growth deviates from percentile curves from one checkup to the next?

A growth curve grid is used to map out the typical growth patterns. When your child deviates minimally from that curve there is generally no cause for concern. For example, going from the 80^th the 70^th percentile and then back to the 80^th percentile at different intervals. Your health professional may become concerned or suggest intervention if your child’s percentile jumps two or more growth curves (for example, moving 10 or 20 points up or down in height or weight for two or more checkups).

Even though growth charts are an important indicator of healthy development, it doesn’t matter if your baby is on the 20^th percentile or the 90^th percentile, as final height and weight are greatly influenced by genetics. So, parents shouldn’t stress about a child’s position on the growth chart as long as they are developing normally and growing according to a consistent curve. As always, it’s best to consult with and follow your health professional’s advice and counsel regarding your child’s growth and weight.