What WHO Growth Charts Actually Are
WHO growth charts are a set of reference curves published by the World Health Organization that describe how healthy children typically grow from birth to age 5. Pediatricians worldwide use them to plot a child's measurements at each visit and follow the resulting curve over time — they are a comparison tool, not a test to pass.
Every chart your pediatrician shows you — for weight, length or height, or head circumference — is built from the same underlying WHO Child Growth Standards dataset, just displaying a different one of five tracked indicators.
Where WHO Growth Charts Come From
The current World Health Organization (WHO) Child Growth Standards were published in 2006, based on the Multicentre Growth Reference Study — a research project that followed healthy, predominantly breastfed children across six countries (Brazil, Ghana, India, Norway, Oman, and the USA) living under conditions known to support healthy growth: good nutrition, non-smoking households, and adequate healthcare access.
This is a meaningful design choice: rather than simply averaging however a general population of children happens to grow, WHO set out to describe how children grow when conditions support their full growth potential — a standard to aim for, not just a reference of what's typical everywhere.
The Five WHO Growth Indicators
WHO Child Growth Standards track five separate indicators, each with its own chart, calculated by a child's exact age in days and separately for boys and girls.
| Indicator | What It Tracks | Typical Age Range |
|---|---|---|
| Weight-for-age | Body weight compared to age and sex | Birth–5 years (and beyond) |
| Length/height-for-age | Length (lying) or height (standing) compared to age and sex | Birth–5 years (and beyond) |
| Weight-for-length/height | Body proportion, independent of age | Birth–2 / 2–5 years |
| BMI-for-age | Weight relative to height, adjusted for age and sex | Birth–5 years (and beyond) |
| Head-circumference-for-age | Head size, a rough proxy for brain growth | Birth–5 years (mainly used birth–2) |
For age-by-age reference values on each of these, see our weight gain by month, height growth by age, and head circumference guide.
Z-Scores and Percentiles, Demystified
A percentile compares a child's measurement to the WHO reference population of children the same age and sex. A child at the 40th percentile is larger than 40% of children of the same age and sex in the reference data, and smaller than 60%.
A z-score (or standard deviation score) is the statistical measurement behind that percentile — it describes how far a measurement sits from the reference median, in standard units. A z-score of 0 sits exactly at the median (50th percentile); positive scores sit above it, negative scores below.
| Z-score (SD) | Approximate Percentile | General Meaning |
|---|---|---|
| Below -3 SD | <0.1st | Well below the typical range |
| -3 to -2 SD | ~0.1st–3rd | Below the typical range |
| -2 to +1 SD | ~3rd–84th | Typical range |
| +1 to +2 SD | ~84th–97th | Above the typical range |
| Above +3 SD | >99.9th | Well above the typical range |
These bands are general reference points, not automatic diagnoses — your pediatrician interprets a measurement alongside the full growth history and your child's overall health.
WHO Charts vs. CDC Charts
In the US, pediatricians use two different chart sets depending on a child's age — a routine, standard practice rather than a sign of any inconsistency.
| WHO Charts | CDC Charts | |
|---|---|---|
| Used for | Birth to 2 years | 2 years and older |
| Reference population | Healthy, predominantly breastfed children, 6 countries | Broader US population, mixed feeding types |
| Describes | How children grow under optimal conditions ("standard") | How children in the US population have typically grown ("reference") |
| Published | 2006 | 2000 (with periodic updates) |
How to Read Your Child's Growth Chart
- Confirm you're using the chart for your child's sex and the correct indicator (weight, height, or head circumference)
- Find your child's exact age along the bottom axis
- Find the measurement along the side axis
- Mark the point where age and measurement meet — the nearest curved line is the approximate percentile
- At the next visit, plot the new point and compare it to the previous one
- Look at the overall trend across several visits, not any single point
Common Growth Chart Misreadings
🏆 "A higher percentile means healthier"
Why it's a myth: A percentile is a comparison, not a grade. A consistently-tracking 10th percentile child can be just as healthy as a consistently-tracking 90th percentile child.
What actually matters- Whether the curve stays fairly consistent over time
- Overall energy, development, and health, not the number alone
📉 "Crossing any line is alarming"
Why it's a myth: Some movement across percentile lines is common, especially in the first two years, as a child settles into their own genetic pattern.
What actually matters- A shift of about one percentile band is usually unremarkable
- A larger, sudden shift across two or more lines is what prompts a closer look
Reading the Chart With Confidence — What to Watch For
- The plotted curve stays fairly consistent across visits
- Measurements are taken with the correct chart for age and sex
- Development and energy are on track alongside the growth pattern
- Premature babies are plotted using adjusted age where applicable
- A sudden or significant shift across two or more percentile lines
- A measurement consistently below the 3rd or above the 97th percentile
- Uncertainty about which chart or age to use for plotting
- A growth concern alongside a change in appetite, energy, or milestones
Reading WHO Charts With Lunara
Manually plotting a chart takes practice, and getting the exact age-in-days and correct chart right for every visit adds up to a lot of careful lookup over the years.
Lunara's growth tracker logs weight, length or height, and head circumference over time and plots them against the full WHO Child Growth Standards curves automatically, giving you an accurate percentile trend without manual chart-reading.
Weekly AI-generated summaries highlight meaningful changes worth noting, and having an organised growth history on hand makes well-child visits easier to prepare for.
See how it works on the growth tracker feature page.
Skip the manual chart-reading —
let Lunara plot the curve for you.
Log a measurement and Lunara plots it against the full WHO Child Growth Standards automatically, so you see a real percentile trend over time. Free to start.
When to Talk to Your Pediatrician About a Growth Chart
| Sign | Why It's Worth Mentioning | First Step |
|---|---|---|
| Crossing 2+ major percentile lines | A larger shift is more likely to reflect a real change worth understanding | Bring your growth log to your next visit |
| Consistently below 3rd or above 97th percentile | Worth confirming the trend and ruling out other causes | Discuss the full history with your pediatrician |
| Unsure which chart or age to use | Using the wrong chart or age can misrepresent the trend | Ask your pediatrician to walk through the correct chart with you |
| Growth concern plus other symptoms | Combined signs are always worth a prompt, fuller review | Contact your pediatrician promptly |
Frequently Asked Questions
WHO growth charts are a set of reference curves published by the World Health Organization that describe how healthy children typically grow from birth to age 5. They cover weight-for-age, length or height-for-age, weight-for-length, BMI-for-age, and head-circumference-for-age, and are used by pediatricians worldwide to plot and compare a child's measurements over time.
The current WHO Child Growth Standards were published in 2006, based on the Multicentre Growth Reference Study, which followed healthy, predominantly breastfed children across six countries under optimal feeding and health conditions. They describe how children grow when conditions support their full growth potential, rather than simply averaging a general population.
WHO charts describe how healthy, breastfed children grow under optimal conditions and are used in the US for children from birth to 2 years. CDC charts are based on a broader reference population of US children of various feeding types and are used from age 2 onward. The switch at 2 years is routine, standard practice.
The five WHO Child Growth Standards indicators are weight-for-age, length or height-for-age, weight-for-length or height, BMI-for-age, and head-circumference-for-age. Each is tracked separately, by exact age in days, and separately for boys and girls.
A z-score (or standard deviation score) describes how far a measurement is from the reference median, in standard statistical units. A z-score of 0 sits exactly at the median; -2 to +2 SD roughly corresponds to the 3rd to 97th percentile range, which is why these bands are commonly used as general thresholds for closer clinical review.
Find your child's exact age along the bottom axis, find their measurement along the side axis, and mark the point where they meet. The curved line closest to that point is their approximate percentile. Repeated visits build a trend line — what matters most is whether that line stays fairly consistent over time, not any single point.
A percentile compares a child's measurement to the WHO reference population of children the same age and sex. A child at the 40th percentile is larger than 40% of children of the same age and sex in the reference data, and smaller than 60%. There is no "best" percentile — a healthy child can be anywhere on the chart.
WHO designed its standards to describe how children grow under optimal conditions, and breastfeeding was established as the biological norm for infant feeding in that framework. This means the WHO charts describe a growth pattern to support, rather than simply describing an average of however children happen to be fed in a general population.
In the US, pediatricians typically use WHO growth standards for children from birth to 2 years, then switch to CDC growth charts from age 2 onward. This is a routine, standard practice recommended by the CDC itself, not something to be concerned about.
No. Some movement across percentile lines is common, especially in the first two years as a child settles into their own genetic growth pattern. A shift of about one percentile band is usually considered unremarkable. A larger or more sudden shift — crossing two or more major lines in a short period — is what typically prompts a closer look.
Yes — official WHO growth chart PDFs and calculators are publicly available, and apps like Lunara plot measurements automatically. Plotting at home can help you follow the trend between visits, but your pediatrician's own plotted chart, using clinically measured data, remains the primary reference.
Yes — WHO publishes separate charts for boys and girls for every indicator, since typical growth patterns differ slightly by sex from birth. Always confirm you're using the chart matching your child's sex when plotting a measurement.
Yes, but pediatricians typically plot using "adjusted age" (also called corrected age) — chronological age minus the number of weeks born early — usually until around 2 years of age, since premature babies often need this extra time to catch up to full-term growth patterns.
The World Health Organization publishes the official WHO Child Growth Standards charts, tables, and software at who.int, including downloadable percentile tables and z-score calculators for each of the five indicators, separately for boys and girls.
Lunara's growth tracker logs weight, length or height, and head circumference over time and plots them against the WHO Child Growth Standards curves automatically, so you can see an accurate percentile trend at a glance without manually reading a paper chart. It's free to start.
The Bottom Line on WHO Growth Charts
A WHO growth chart is a comparison tool built from careful research, not a test your child needs to pass. The line your child's measurements draw over time — steady and consistent — is what your pediatrician is actually watching, far more than the exact percentile at any single visit.
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