How to Read Baby Growth Charts

Growth charts are one of the most important tools your pediatrician uses to track your baby's development. Understanding how to read them helps you make sense of your baby's measurements and know when a pattern warrants discussion with your doctor.

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Key takeaways

  • Growth charts show how your baby compares to other healthy babies of the same age and sex
  • The trend over time matters far more than any single measurement
  • WHO charts are recommended for children under 2 years; CDC charts for ages 2 and older
  • Growth charts plot three key measurements: weight-for-age, length-for-age, and head circumference-for-age
  • A baby who consistently follows any percentile line is growing normally, whether it is the 10th or the 90th

What is a growth chart?

A growth chart is a graph that shows how a baby's measurements compare to a large reference population of healthy children of the same age and sex. The chart displays curved lines called percentile lines (typically the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles). When your baby's measurements are plotted on the chart over time, they create a growth curve that shows their individual growth pattern.

The three key measurements

Weight-for-age

This is the most commonly tracked measurement. Your baby is weighed naked (or in a clean diaper) on a calibrated infant scale. Weight is sensitive to short-term changes in nutrition and hydration, making it the first indicator to change if there is a feeding issue.

Length-for-age (height-for-age after age 2)

Babies under 2 are measured lying down (recumbent length). After age 2, standing height is measured. Length reflects longer-term nutritional status and genetic potential. It changes more slowly than weight and is harder to measure accurately in squirmy infants.

Head circumference-for-age

Head circumference (occipitofrontal circumference) is measured by wrapping a flexible tape around the largest part of the head. It tracks brain growth and is measured routinely until age 2 or 3. Rapid increases or decreases may prompt further evaluation.

How to read the chart step by step

  1. Find your baby's age on the bottom axis (x-axis). The horizontal axis shows age in months (or weeks for newborns).
  2. Find the measurement on the vertical axis (y-axis). This shows weight in kilograms or pounds, length in centimeters or inches, or head circumference in centimeters.
  3. Plot the point where age and measurement intersect. This is where your baby falls at this specific time point.
  4. Identify the nearest percentile line.The curved lines represent the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles. If your baby's dot falls on the 50th percentile line, half of healthy babies weigh more and half weigh less.
  5. Look at the trend over multiple visits. Connect the dots from previous measurements. A healthy growth curve generally follows along a percentile line, rising steadily over time.

WHO vs CDC charts: which one to use

The CDC recommends using WHO growth standards for children from birth to 24 months of age. The WHO charts are based on data from healthy, breastfed infants raised in optimal conditions across six countries, making them a true growth standard (how children should grow). For children aged 2 to 20 years, the CDC growth reference charts are used. These were developed from U.S. survey data and reflect how children in the U.S. actually grew. The practical difference is that WHO charts may show breastfed babies as growing more normally, whereas CDC charts were developed from a population that included more formula-fed babies.

When the growth pattern is a concern

A growth pattern may warrant further evaluation when a baby crosses two or more major percentile lines (either up or down), when weight-for-length falls below the 5th percentile or above the 95th percentile, when weight, length, and head circumference are on very different percentile tracks (with the exception of familial patterns), or when the growth curve flattens or declines over two or more measurement points. One measurement alone rarely tells the full story. Your pediatrician considers the overall pattern, your baby's feeding, development, and family size patterns when evaluating growth.

Frequently asked questions

What growth chart should my pediatrician use?
The WHO growth standards are recommended for children under 2 years old, regardless of feeding method. For children aged 2 and older, the CDC growth charts are typically used in the United States. The WHO charts describe how children should grow under optimal conditions, while CDC charts describe how children in the U.S. actually grew during a specific time period.
How often should my baby be measured?
The AAP recommends measuring weight, length, and head circumference at every well-child visit. These are typically scheduled at birth, 3-5 days, 1 month, 2 months, 4 months, 6 months, 9 months, 12 months, 15 months, 18 months, and 24 months. More frequent measurements may be needed if there are growth concerns.
My baby dropped from the 75th to the 50th percentile. Should I worry?
A single drop of one percentile line is often normal, especially during the first 2 years when babies settle into their genetic growth pattern. Concern arises when a baby crosses two or more major percentile lines, when weight loss is rapid, or when the drop is accompanied by other symptoms. Discuss any changes with your pediatrician at your next visit.
Are growth chart percentiles the same as grades?
No. Growth percentiles are not grades. Being at the 25th percentile does not mean your baby is failing. It means 25% of healthy babies weigh less and 75% weigh more at that age. A baby at the 10th percentile who stays at the 10th percentile is growing perfectly normally. The trend matters more than any single number.
Why does my baby have different percentiles for weight and length?
It is completely normal for babies to have different percentiles for weight, length, and head circumference. A baby might be at the 80th percentile for length but the 50th for weight, meaning they are long and lean. As long as each measurement follows its own consistent curve, this is typical healthy variation.

Bottom line

Growth charts are tracking tools, not report cards. Your baby's percentile is far less important than their growth trend over time. A baby who consistently follows the 15th percentile is growing just as healthily as one following the 85th. Work with your pediatrician to understand your baby's unique pattern, and ask questions any time a measurement concerns you.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

All content follows our editorial policy and is reviewed against published clinical guidelines.

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