By: Nicole Anania, DO, MS, FAAP
When you go to the pediatrician for a
well-child check, you'll always review your baby's or child's growth together. It's probably the most important piece of data the doctor tracks. That's because it can show so much about your child's vitality.
Your child's first 2 years: a major growth period
In the first 2 years, we use one growth chart that looks at a child's head's circumference (a measurement of the widest part of their head), as well as their weight and length. We watch for changes in the size of head circumference in infancy because we want to know that the brain is growing.
Why growth percentiles are not like grades in school
What we want from a growth chart is to map out the growth trend for children. Unlike school grades that we hope are always as high as possible, for growth we hope for consistency. When your child comes in at the 10th percentile, it's really no better or worse than coming in at the 90th. What we care about most is the trend at which your baby or child gains weight, height or head circumference.
After
age 2, you can use the same growth chart to track your child's growth until they're 20 years old. In addition to weight and height, we also look at
body mass index (BMI). BMI helps show whether a child’s weight is a healthy match for their height. Are they at risk for
overweight or are they too lean?
Factors that influence a child's growth
A variety of factors, including genetics, environment, nutrition, activity and health problems, can influence how your child grows. Parents, pediatricians and nurses have been using growth charts since the late 1970s to track growth in infants and children. The charts were revised in 2000, when research showed that data for the first charts didn't accurately reflect the cultural and ethnic diversity of our communities.
It is important to review your baby’s or child’s growth frequently so that you and your pediatrician can identify any changes to the trend. Often, simple steps can be taken to help ensure your child’s ongoing healthy growth.
Growth chart downloads
If you're interested in tracking your child’s growth between visits, you can download the age‑specific growth charts below.
Males
Females
How to follow your child's growth chart
When you're looking at a growth chart, focus on how your child is changing over time. One static point on the growth chart isn't as useful as evaluating 5 data points over time.
As you follow your child's growth chart along from infancy into toddlerhood, you'll notice frequent changes. As your child gets older, these changes may happen less often. It is the rate and trend in your child's growth that is important, rather than the specific number.
Why you shouldn't focus on the number
Your child is at the 25th percentile, you don't know how to interpret that number without looking at the past numers and percentiles. Don't focus soley on the number. Ask your pediatrician, family doctor or nurse practitioner to help you understand what the growth trend shows.
Tracking growth: a key part of each well-child visit
One of the most important parts of a well-child checkup is the review of a child's growth. Growth can be a reflection of a child's overall health and nutrition. It can also help identify underlying medical conditions. So, it's important to understand what your doctor or nurse practitioner says about your child's growth.
If your doctor doesn't have a computer in the examination room, ask to see the growth chart on paper or on a screen in the office. Many parents find it exciting to look back and see how much their child has grown since the last visit. The human body is pretty amazing—your baby will double their weight by about 6 months and triple it by around 1 year.
What z-scores mean on a growth chart
At times, your pediatrician may use additional information and charts to help them understand your child's weight and growth over time. In particular, the doctor may use extra information when your child's measurements fall above or below the percentile curves on the growth charts.
Z-scores may be part of the additional information used by your pediatrician. Z-scores allow pediatricians to understand and compare children's weights even when they are above or below the percentile growth curves.
In the table below, the z-score associated with each major percentile and weight on a growth chart is being shown for a 6-month-old female. For simplicity, the weight in pounds have been rounded up to the nearest pound and the z-scores are displayed as whole and half numbers:
Weight (kg) | 5.651 | 6.020 | 6.403 | 6.800 |
7.211 | 7.636 | 8.077 | 8.531 | 9.001 |
Weight (lbs) | 12 | 13 | 14
| 15 |
16 | 17 | 18 | 19 | 20 |
Z-Score |
-2 |
-1.5 |
-1 |
-0.5 |
0 |
0.5 |
1 |
1.5 |
2 |
Percentile |
3rd |
5th |
15th |
25th |
50th |
75th |
85th |
95th |
97th |
Remember that a z-score is just a number.
The number may be positive (greater than 0) or negative (less than 0).
A child with a positive z-score, or a number higher than 0, weighs more than the average child of the same age and sex.
A child with a negative z-score, or a number lower than 0, weighs less than the average child of the same age and sex.
A child with a z-score of 0 has a weight that is equal to the average weight for a child of that age and sex (50th percentile on the growth chart). It is not the lowest weight or the highest weight for a child of that age and sex; it is in the middle of the weights for children of that age and sex.
Using stairs or steps as an example can also be helpful to understand z-scores. A child with a z-score of -2 is like going down 2 steps from the main floor. A child with a z-score of 2 is like going up 2 steps from the main floor. Both children are 2 steps from the average child (the mean).
Links to World Health Organization (WHO) growth charts that use z-scores:
If you have questions about your child's growth
If you have a challenge understanding how your child is growing or how the growth chart is presented, keep asking for clarification. It's OK if you don't understand the presentation of facts on these charts. Have confidence to speak up and ask the doctor or nurse practitioner to explain it.
More information
About Dr. Anania
 Nicole Anania, DO, MS, FAAP, served as the Implementation Scientist on the American Academy of Pediatrics Faltering Weight Clinical Practice Guideline. Most recently, she was a Professor of Pediatrics at the University of Kentucky and Medical Director for Inpatient Pediatrics at Med Center Health in Bowling Green, KY. Prior to that, she served as a Master Clinician and Director of Quality Improvement for the Outreach Division of Ann & Robert H. Lurie Children's Hospital of Chicago and has extensive experience working with children with medical complexity and faltering weight.
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