Baby Growth Charts: Birth to 36 Months

Track your baby's height, weight, and head circumference to ensure they're developing properly.

Pediatrician Measuring Baby Weight on Scale
Photo: Africa Studio / Shutterstock

Every baby grows at a different pace. Given the wide range of "normal" sizes, it's hard to know whether your child measures up to standards. That's why pediatricians track physical developments like length, weight, and head circumference with baby growth charts.

What is a Baby Growth Chart?

Genetics plays a major role in a baby's physical development – as do factors like environment, nutrition, activity level, and health condition. Even breastfed babies have different weight and height standards than their formula-fed counterparts. According to the Centers for Disease Control and Prevention (CDC), breastfed babies tend to gain weight slower than formula-fed babies during the first 12 months of life. Thanks to discrepancies like these, many parents wonder what a "normal" baby should look like, and they worry if their little one is bigger or smaller than other infants.

To answer these questions, the medical community has created growth charts that help pediatricians and parents understand if a child is growing at a healthy rate by tracking babies' height, length, and head circumference from birth to 24 months and beyond. In 1977, the National Center for Health Statistics (NCHS) created the first growth chart. Since then, the CDC and The World Health Organization (WHO) have each created growth charts.

Growth charts can feel intimidating to some parents, but it is important to remember that a growth chart is one of many tools your doctor uses to help see how well your child is developing. You'll find links to all charts at the bottom of the page.

What Do Baby Growth Charts Measure?

Most charts measure length, weight, and head circumference. Pediatricians take these measurements during your baby's regular wellness exams. Plotting the information on a growth chart lets them patterns and consistencies. Growth charts compare your baby's measurements to those of the average infant. It is important to note that separate growth charts exist for males and females and children with specific developmental conditions such as Down Syndrome or premature birth.

Here is what your doctor will measure.

Length

Using a tape measure, a doctor determines the distance from your baby's head to their feet – usually while they're stretched on an exam table. Some parents may wonder if the length measurements on a growth chart can help predict future height; they don't. The length measurement is meant to help identify if your baby is growing at an expected rate for their age.

Weight

A baby scale provides the best weight measurements. If your baby is under 12 months, you'll probably need to take off their clothes before laying them on the scale. Typically, children whose weight falls between the 5th and 85th percentile are considered healthy. Some kids may fall below 5% or above 85%, which is not necessarily an indicator of poor health but is something that a doctor would want to monitor.

Head circumference

Also taken with a tape measure, head circumference clues you into your baby's brain development. A too-big head may signal a condition called hydrocephalus, characterized by excess fluid on the brain. On the other hand, if the distance around the head seems small, the baby may have developmental delays. In a study published in Nature, researchers found that atypical head circumference growth in male infants was a reliable predictor for neurodevelopmental disorders. While more studies need to be done, this shows the importance of how growth charts can cue doctors into potential health issues.

How to Read Baby Growth Charts

Growth charts can be hard to decipher at first glance. Here's how to read WHO and CDC baby growth charts for length and weight, which are linked at the bottom of the article:

  1. Locate your child's length or weight (depending on what you're measuring) on the grid's left- or right-hand side also called the Y-axis.
  2. Find your baby's monthly age on the top of the graph, also called the X-axis.
  3. Follow the lines until they intersect. They should cross somewhere along the curves, which represent percentiles.
  4. Follow the curve to see the percentiles on the right-hand side of the graph. The percentile lines show your baby's measurements compared with other babies' measurements.

Generally speaking, higher percentiles mean your kid has bigger measurements than average – and vice versa for smaller percentiles. For example, if the curved line is "75" when measuring length, then your baby is in the 75th percentile for length. This means that 25% of babies are taller than your child, and 75% are shorter than your child.

How to Interpret the Data

Instead of analyzing the actual measurements, doctors pay attention to patterns and consistencies on the growth charts. A constantly growing, proportionate baby doesn't raise any red flags – but a noticeable change in measurements should be closely examined.

For instance, having a lower weight and length for age isn't usually worrisome; it might mean your baby has a genetic predisposition to being short and thin. But if they go from a high-weight percentile (like 80th) to a low-weight percentile (like 25th), they may not be eating enough. Your baby might also have a health condition that causes weight loss, such as celiac disease. On the other hand, gaining lots of weight for your baby's age could mean that they are eating too much, which could lead to future health and weight problems.

Remember that all babies grow at different paces. Measuring at the 50th percentile isn't better or worse than the 15th, 70th, or 99th percentile. As long as your baby is experiencing normal growth patterns, he will likely grow up happy and healthy.

The Difference Between WHO and CDC Growth Charts

It is important to understand that the growth charts used by the WHO and the CDC differ. The WHO growth chart describes measurement standards of healthy children worldwide.

The CDC growth chart describes American children based on the growth data of kids living in the US since 1977. The CDC updated its growth chart in 2000 to include considerations such as diverse racial and ethnic backgrounds and a new age-based BMI that screens for childhood obesity. The updated growth chart also considers the differences in weight growth between breastfed and formula-fed babies.

The CDC recommends that pediatricians and parents use the WHO growth charts for babies under 24 months and the CDC growth chart for children 2 years and up.

WHO Growth Charts

CDC Growth Charts

INTRO HERE ON CDC CHARTS

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