There's one thing you can expect at every well-child visit: Your baby will be weighed and measured. The pediatrician will then plot those measurements on an infant growth chart to help keep tabs on how your little one is growing, both over time and compared to national averages.
Although your child's pediatrician is on the lookout for any drastic increases or decreases over a short period of time, know that it's often totally fine to have a not-so-average growth curve.
What is an infant growth chart?
An infant growth chart is just what it sounds like: a chart that tracks babies' growth over time and as compared to other babies.
Growth charts have been used since 1977 to track baby development. The charts we use today come from the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). The CDC growth charts were revised in 2000 after measuring and weighing thousands of children across various cultures and ethnicities to set averages for weight, height and head circumference for boys and girls throughout infancy and childhood.
These charts are used to track and compare your child’s measurements against these standard averages to assess how she’s growing through the years. Just remember: Depending on genetics, environment, nutritional intake and activity level, what’s "normal" from baby to baby can vary greatly.
What do infant growth charts measure?
Infant growth charts measure:
- Weight, which is measured in pounds and ounces after taking your little one’s clothing off (she can either have a clean, dry diaper on or off) and placing her on the baby scale
- Length (height), which is taken for children under 2 years old using a tape measure while the baby is lying down to fully stretch her out; for kids ages 2 and older, height is measured while they're standing up
- Head circumference, which is taken by wrapping a tape measure around a baby’s head
At each visit, your baby’s pediatrician will plot your child's measurements on a growth curve to monitor her individual growth over time. Boys and girls will be measured on different growth charts, as they tend to grow at different patterns and rates.
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How do you read infant growth charts?
These charts can be hard to follow! Start by finding your baby’s measurement (length, weight or head circumference) on one axis. Then find her age on the other axis. Follow both on a straight line until they meet in the middle of the grid. That will give you your baby’s growth percentile.
When you’re looking at a growth chart, it’s important to focus less on an individual statistic and more on your child’s curve over time, and whether or not that’s maintaining some sort of consistency.
Here’s what to know about each data point.
Weight growth charts
Children experience the most rapid weight gain during infancy. Most babies double their birth weight between 4 and 6 months and triple it by 1 year old.
Things start slowing down between 1 and 2 years old. Babies tend to gain only about 5 pounds during this time, because they're more active and don't eat as often. Most children continue to gain weight at this rate between 2 and 5 years old.
If your baby weighs in at a high percentile: Maybe your baby has been on the bigger side since birth — or one or both parents have larger body frames. Regardless, this probably isn't cause for concern. Your baby’s pediatrician will, of course, look for signs of medical conditions during the exam, but if there are none to be found, then the doctor will likely just keep an eye on your little one's weight at upcoming visits.
If your baby is gaining a lot of weight rapidly over the course of several visits: Of course you don't want to put a baby on a diet (they need calories and fat), but your doctor will likely try to determine whether you're overfeeding her. Remember, the goal isn't for your child to lose pounds, just to not gain an excessive amount of weight. You and your doctor can discuss how much and how often you're feeding her as well as ways to prevent overdoing it.
If your baby has lost a lot of weight since her last checkup: The doctor will probably ask about her diet (what she's eating and how much), whether she's had any health problems (such as chronic vomiting or diarrhea), and of course do a physical exam. This will help the pediatrician determine if there's an issue causing the weight loss and, if there is, work with you on solving it.
Head circumference charts
Your baby’s pediatrician wants to make sure your baby's brain is growing and developing normally, and head size is an important factor in determining that. The head doesn't grow much after the fontanelles (soft spots) close at around 18 months, though pediatricians still usually measure head circumference in children up to age 2 (and sometimes even until age 3). Again, head size is mostly genetic — so if you or your baby's other parent has a small head, your child may have a petite one too, and vice versa.
To measure your baby's head, a nurse will wrap a flexible measuring tape around the broadest part of your baby's forehead, just above the ears and at the midpoint of the back of the head.
If your baby's head is significantly larger or smaller than the last checkup, the doctor will look for signs of developmental delays or illness during the physical exam (just as in any checkup). If everything appears normal, the pediatrician will likely take no immediate steps and just wait until your next appointment to check your baby's progress. If, however, the pediatrician is concerned with your baby's percentile at the next visit, it may be time to further investigate the following (rare) scenarios:
If your baby's head is measuring very large: The pediatrician might order a CT scan or ultrasound to check for hydrocephalus (extra fluid surrounding the brain).
If your baby's head is measuring small or is not growing: Your baby's doctor may be concerned about failure to thrive (when a child doesn't take in enough calories or is unable to utilize them and doesn't grow properly as a result). But it's much more likely that your baby’s pediatrician would notice a drop in weight and length on your child's growth charts first before noticing the decrease in head percentile. And in very rare cases, small head size or lack of growth can signal brain malformations — although again, that scenario is quite uncommon.
Length growth charts
Babies grow most rapidly during their first year of life — 10 inches in length on average. Gains in length slow down after age 1, and from age 2 until adolescence, kids usually grow about 2 1/2 inches per year.
The nurse at the pediatrician's office will lay your baby down on the exam table and gently stretch her out to measure her length from the top of her head to the bottom of her heel. Because your baby may be fidgety or scrunch up her legs during this process, length can be the least accurate of all the growth chart measurements taken at your child's checkups.
If your baby is gaining length at each appointment and is also at a healthy weight: She's taking in an adequate amount of calories and is growing normally.
If your baby is measuring very long and is also gaining weight rapidly: There's a chance that you could be feeding your little one too much and/or too often. Your doctor will talk to you about your baby's eating habits and, if necessary, counsel you on how to avoid overfeeding (for example, by learning to read your baby's hunger cues and by not letting her use your breast as a pacifier if you're nursing).
If your baby has always been on the short side: If you or your baby's other parent (or both of you) are petite, your baby's length percentiles may be on the small side too.
If your baby is not gaining length or weight (or is gaining very slowly): She may have what doctors call a failure to thrive, which is when your baby is not receiving sufficient calories or her body can't use the calories she needs to grow. Failure to thrive has many different possible causes, so if the doctor suspects it, the next step is to determine the underlying problem and then work to treat that issue.
What does "percentile" mean on a baby's growth chart?
The percentiles you've probably heard so much about are derived from a chart of average heights or lengths, weights and head sizes. Developed by the World Health Organization (WHO), the percentiles on infant growth charts are based on a study of breastfed children (in six different cities in six countries, who grew up in optimal conditions).
Both the Centers for Disease Control (CDC) and American Academy of Pediatrics (AAP) recommend doctors use the WHO charts for babies under age 2. Pediatricians use a second set of charts created by the CDC for children from 2 to 20 years old to measure standing height and weight. Both charts are different for boys and girls, because boys tend to be larger and grow faster than girls.
After your baby's measurements are taken, her practitioner will plot them out on this chart (or plug them into a computer) to find your baby's percentiles compared with the national averages. For example, if your child is in the 75th percentile for weight, 75 percent of other little girls her age weigh less than she does.
To get a clear picture of growth, your doctor will also consider the relationship between weight and length. While the percentiles don't have to match up exactly, they should be within a 10 to 20 percent range of each other. If length is 85th percentile but weight is 15th percentile, your baby might be underweight. The other way around? Your baby may be overfed.
What is considered a "normal" percentile range?
Don't be concerned if your baby is above or below average — a healthy baby can come in any size, no matter whether that's in the 90th or 10th percentile. Your practitioner is looking at lots of factors to confirm your baby is growing as expected, including:
- Your child's growth over time
- The results of your baby's physical exam
- Whether your child is hitting developmental milestones
- Whether your child is sleeping and eating normally (for her)
- If she seems happy and is interacting well with her parents and caregivers
- Growth spurts
Your pediatrician will let you know if there's any cause for concern after taking these factors into consideration.
Is a higher percentile better for babies?
A higher reading on a growth chart is not necessarily a good or a bad thing. Much of a child's size depends on genetics — meaning if either parent is tall or big-boned or has a larger-than-average head size, the baby more likely will too. There’s no one ideal number for any child — a variety of factors paint the complete picture of your baby's health.
What if there's a sudden change in my baby's measurements?
When taken in consideration with other measures, sometimes a baby whose percentiles increase or decrease dramatically can signal a problem.
But most of the time what appears to be a sudden growth shift is just the result of a miscalculation — one made at the current visit or a previous one. Babies can be wriggly, and that can easily affect the results.
And sometimes, a growth shift can indicate that a baby who was born on the large side or who grew quickly at first, for example, is slowing down as she gets closer to her predetermined genetic size.
When should I worry about my baby’s growth?
It’s important to not compare your baby to others. As long as she’s growing steadily on her individual curve, there’s often no need to worry. And after the first year, her growth pattern will slow down.
Though you know your baby best. If you have any concerns about your baby’s growth, talk to her pediatrician.
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