Paediatric percentiles in practice: WHO, criteria, and charts
Weight, height, BMI, and growth velocity in daily clinical practice
In paediatric nutrition, a percentile is not a diagnosis on its own: it is context. A child at the 10th percentile is not necessarily undernourished, and one at the 90th is not necessarily obese. What matters is **trajectory** (growth velocity), age, sex, and the reference used. This guide summarises practical criteria for practice.
Which reference to use: WHO vs. national
National references (e.g. country-specific growth charts): may better reflect local populations at certain ages.
Practical rule: choose one reference and keep it for all visits of the same patient. Switching tables between visits invalidates trajectory comparison.
Weight, height, and BMI: what to check each visit
Height for age: chronic linear growth indicator. Plateau → investigate nutritional or medical causes.
BMI for age: useful from age 2 for relative overweight or underweight. In infants < 2 years, prioritise weight-for-length and head circumference.
Head circumference (0-24 months): mandatory in infant checks; marked deviations require medical referral.
Growth velocity: the indicator that matters most
- Does the patient cross percentiles up or down in 3-6 months?
- Is height growth velocity adequate for age?
- Is there weight-height decoupling (e.g. weight rises, height stalls)?
Crossing 2 or more percentile channels in a short period (especially downward in height) is a warning sign requiring broader medical assessment, not diet adjustment alone.
Z-scores vs. percentiles
- z = 0 → median (50th percentile)
- z = +2 → approx. 97.7th percentile
- z = -2 → approx. 2.3rd percentile
In clinical protocols and WHO work, z < -2 or z > +2 for BMI-for-age is often used as a risk threshold (overweight/obesity or underweight), always interpreted with context and trajectory.
Recording in practice: non-negotiable measurements
1. Weight on calibrated scale, minimal clothing, same time of day if possible
2. Height on stadiometer (not home tape for clinical follow-up)
3. Corrected age in preterm infants until 2-3 years per centre protocol
4. Exact measurement date linked to measuring professional
5. Same reference (WHO or other) at every visit
Without these five points, the chart is decorative, not clinical.
Communicating percentiles to families without alarming
- «They are on channel X of the WHO growth curve, which is within expected range for their age.»
- «What we watch is that they follow their own curve; today the trajectory is stable.»
- «We will repeat measurement in 3 months to confirm the trend.»
A patient portal with a visual chart helps families understand evolution without misreading a single number.
See paediatric patients and need percentiles in the file?
NutriManager calculates and charts WHO percentiles with evolution between visits — no separate spreadsheets.
Frequently asked questions
WHO recommends BMI-for-age from 2 years complete. Before that, prioritise weight-for-length, weight-for-age, and head circumference by age.
Between the 3rd and 97th percentiles (or z between -2 and +2) is usually typical, provided trajectory runs parallel to curves without sharp crossings. The goal is not «reaching the 50th» but growing appropriately.
Yes. The paediatric nutrition module includes WHO 0-19 percentile charts for weight, height, and BMI, with history between visits in the patient file.
Yes, but interpret cautiously: height may lag peers of the same age. Assess pubertal stage and growth velocity; coordinate with paediatrics in borderline cases.
Record in the clinical history that the family authorises anthropometric recording of the minor. If sharing charts via portal, access is audited in the digital file.