This article is the start of a four-part series on children’s growth charts. The series is intended to describe how the charts were developed, how to interpret them, some of the controversy surrounding race and ethnicity, and how to track your child’s growth.

An introduction

Most parents are introduced to the idea of growth charts during early visits to the pediatrician – when your baby’s height, weight, and head circumference are first measured – and then at every subsequent well-child checkup.

The growth charts serve a couple of purposes. First, is to figure out a baseline – where do your child’s measurements fall along the growth curves relative to other children of the same age and gender right after they are born.

Secondly, the doctor will record these measurements over time to see if your child is, in fact, growing as expected. Growth charts are standard way to do this so that you know if your child’s growth is on track.

How were these growth charts designed?

Growth charts were developed by national and global health organizations – like the Centers for Disease Control (CDC) for US growth and the World Health Organization (WHO) for global growth patterns. These organizations measured thousands of children of diverse ethnic and racial backgrounds and determined the average height and weight of those children by age and gender. They then analyzed all of the measurements to see how children were children fell on either side of the average. The growth chart reflects the percentage of the population that falls above or below the average.

The CDC’s most recent growth charts were published in 2000, replacing the 1977 version. The 2000 version introduced the body mass index chart. One drawback of these charts, that some clinicians are concerned about, is that the charts do not show ethnic differences, but, instead, are a survey of all types of children.

What do growth charts track?

Growth charts are used to track a child’s development over time. Typical growth charts allow you to track height and weight. For babies under 36 months of age, head circumference is charted. More recently, doctors have been calculating and tracking body mass index and, sometimes waist circumference to height ratios to determine a child’s risk for obesity, childhood diabetes, and heart disease.

Given that girls and boys grow differently from each other, the growth chart used will depend on your child’s gender. It may also depend on your child’s age. The CDC has charts for children 0-36 months old, as well as 2-18 years old. Generally speaking, if your child is between 24 and 36 months old, the 0-36 month chart is used if you measure your child’s length while they are lying down; the 2-18 year chart is used if your child stands when their height is measured.

A list of charts is available on the CDC website, about half-way down on the Clinical Growth Charts page.