Down Syndrome (Zemel) Growth Charts

Children with Down syndrome have distinct growth trajectories from the general pediatric population — characteristically shorter stature, different weight-to-height patterns, and different head-circumference growth velocities. Plotting them on standard CDC or WHO curves consistently misclassifies their growth status.

The Zemel et al. (2015) Down syndrome-specific growth charts, published by Children's Hospital of Philadelphia, are the recommended reference for pediatric clinical care of children with Down syndrome. Each calculator on this page uses the Zemel reference.

When to use these calculators

Use the Down syndrome-specific charts whenever the child has confirmed Down syndrome (trisomy 21). The Zemel charts capture the typical Down-syndrome growth pattern; standard charts will indicate growth failure where the child is actually tracking normally on the syndrome-specific reference.

Frequently Asked Questions

Why are Down syndrome growth charts different?

Children with Down syndrome have shorter average stature, a different weight-velocity pattern, and slower head growth in the first 2 years. The Zemel chart's reference distribution reflects these patterns; applying the general CDC chart over-diagnoses growth failure.

Does the chart still use CDC-style percentiles?

Yes — the Zemel chart uses the same z-score / percentile framework as CDC and WHO. Only the reference distribution differs. A child at the 50th percentile on the Zemel chart is at the average for children with Down syndrome.

Are these charts used in adult care?

The Zemel charts extend to age 20. For adult care of individuals with Down syndrome, growth measures shift to other clinical screens (BMI, body composition, comorbidity screening).