Understanding Your Child’s Growth Chart

Growth charts are tools that medical professionals use to track trends in your child’s growth. They are also used to diagnose conditions that indicate growth issues, such as obesity or failure to thrive. For more information about how growth charts are used and interpreted, read on.

Understanding when to use which growth chart:

The Centers for Disease Control and Prevention’s website provides growth charts used for the majority of typically developing kids. It is important that medical professionals use the right growth chart for their patient.

  • For kids < 2 years old:  The growth charts labeled 0-2 years old from the World Health Organization should be used until age two. Recently, growth charts for this age were updated using data that is representative of a wider range of ethnicities and primarily breastfed babies.
  • The “Birth-36 months” growth charts:  These should be used when the child’s length is measured recumbently (lying down). If the practitioner is able to get repeatedly accurate standing height measurements of the child age 24-36 months, then the “2-20 years old” growth chart would be used to plot height and BMI. Weight-for-length is plotted using recumbent length, and BMI is calculated and plotted using standing height.
  • The “2-20” growth charts: These are used for typically developing kids in this age range, and for kids ages 2-3 if their height has been measured standing up. These are also used for kids with special needs or specific diagnoses, such as Down Syndrome and Cerebral Palsy, according to recent recommendations. However, it is imperative that a trained medical professional interpret growth of kids with special needs on standard growth charts. I find it useful to use both standard growth charts and growth charts designed for kids with specific diagnoses as multiple pieces of information in overall growth assessment.

BMI Measurements:

  • Weight for Length and BMI. This single data point is very important, as opposed to the other growth measurements where the overall trend is more important. These growth charts are used diagnostically as follows:
  • Weight-for-length or BMI < 5th percentile. This is considered “underweight”, which means that the infant or child does not have adequate body mass for how long he or she is. Kids who are underweight may be at higher risk for nutrient deficiencies, compromised immune function, lethargy, impaired cognitive development, and more. These cases should be referred to a pediatric dietitian. If underweight status worsens over time or is a chronic issue, the child may be diagnosed failure to thrive.
  • BMI 85th – 94th percentile. This is diagnosed as overweight. Weight loss is not recommended for these kids, but rather weight maintenance. Then as their heightcontinues to increase, the BMI will normalize.
  • BMI > 95th percentile. This is diagnosed as obese. These kids should be referred to a pediatric dietitian for assessment and a weight management plan.
  • Note, children under 2 years old are not diagnosed overweight and obese. This is because growth patterns are very different in infants than older kids. Many factors should be taken into consideration by the trained medical professional for infants who have weight-for-length > 95th percentile before changes to their diet intake are made.

“Within Normal Limits”

This phrase describes the percentiles of the growth chart that are considered to be within a normal range of growth for kids that age. The normal range concept applies mostly to the BMI growth chart and the Weight-for-Length growth chart. BMI is within normal limits if it falls between the 5th and 85th percentiles.

It’s all about the trend.

When it comes to weight and length or height, in most cases, the bigger picture is more important than individual measurements. This means that as long as your child’s growth is “tracking along its usual curve”, his or her growth is probably normal for them. If weight or length/height drop or increase more than two growth channels over a span of 6 months, this is cause for concern and needs further evaluation by the pediatrician and dietitian.

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