What are the expected height, weight, body mass index and head circumference for a 7‑year‑old girl with Down syndrome according to the UK‑WHO growth reference chart?

Growth Parameters for 7-Year-Old Girls with Down Syndrome

For a 7-year-old girl with Down syndrome, you must use Down syndrome-specific growth charts rather than standard UK-WHO charts, as children with Down syndrome follow distinctly different growth trajectories that would be misclassified as pathologically short on typical reference curves.

Critical Chart Selection

• Down syndrome-specific growth charts are essential because children with this condition have characteristic growth patterns that differ substantially from the general population—using standard UK-WHO or CDC charts will systematically misclassify these children as having growth failure when they are actually growing appropriately for their condition 1

• The standard UK-WHO framework recommends WHO charts for children under 24 months and CDC charts for ages 2-19 years in typical children, but this does not apply to children with genetic syndromes like Down syndrome 1, 2

Why Standard Charts Are Inappropriate

• Children with genetic conditions such as Down syndrome require syndrome-specific growth references because their constitutional growth potential differs from the general population 3

• Plotting a child with Down syndrome on standard charts would place them well below the 2nd percentile (the threshold indicating potential adverse health conditions), triggering unnecessary medical evaluations and potentially harmful interventions 3, 4

• The UK 1990 charts identify children below the 2nd centile as requiring medical assessment, but this threshold is designed for typically developing children and would incorrectly flag most children with Down syndrome 4

Proper Assessment Approach

• Growth should be monitored longitudinally using Down syndrome-specific charts to establish the child's individual growth trajectory rather than focusing on single measurements 1

• Serial measurements plotted on appropriate syndrome-specific charts every 3-6 months allow tracking of growth velocity, which is far more informative than isolated measurements 3, 2

• The assessment should consider the child's previous growth pattern and overall health status within the context of Down syndrome 1

Key Parameters to Monitor

For a 7-year-old girl with Down syndrome, you should track:

• Height-for-age on Down syndrome-specific charts 3
• Weight-for-age on Down syndrome-specific charts 3, 5
• BMI-for-age calculated as weight (kg) divided by height (m²), plotted on Down syndrome-specific BMI references 3, 6
• Head circumference if syndrome-specific references are available 3

Common Pitfalls to Avoid

• Do not use standard UK-WHO or CDC growth charts for children with Down syndrome—this is the single most important error to avoid, as it will lead to misdiagnosis of growth failure in a child who is growing normally for their genetic condition 3, 1

• Do not initiate growth hormone evaluation or other interventions based on low percentiles on standard charts without first confirming the measurements are abnormal on syndrome-specific references 3

• Avoid relying on a single measurement; growth velocity over time using multiple data points is essential for distinguishing normal constitutional growth from pathologic decline 1, 2

• Be aware that measurement technique matters—ensure accurate standing height (not recumbent length at this age), calibrated equipment, and trained personnel 3

Clinical Decision Algorithm

1. Obtain accurate measurements of height, weight, and head circumference using proper technique 3
2. Plot all measurements on Down syndrome-specific growth charts (not standard UK-WHO charts) 1
3. Compare current measurements to the child's previous trajectory on these syndrome-specific charts 1
4. Assess growth velocity by reviewing serial measurements at 3-6 month intervals 3, 2
5. Only pursue further evaluation if the child is falling off their established percentile curve on the Down syndrome-specific charts or if measurements fall below the 2nd percentile on those syndrome-specific references 3, 1