Child Growth Chart (0-24 Months)

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Baby Weight Percentile: What It Actually Means

who vs cdc growth charts difference

WHO or CDC Growth Charts: Which One Should You Use?

Both charts measure the same things, weight, length/height, head circumference, but they were built with different purposes, which is why each is recommended for a different age range.

Prescriptive standard vs. descriptive reference

The WHO curves (2006) are a "standard": they describe how children grow under environmental conditions considered ideal (predominantly breastfed, no maternal smoking, good socioeconomic conditions), based on data from over 8,000 children across six countries.
The CDC curves are a "reference": they statistically describe how American children actually grew in historical national surveys, without filtering for ideal feeding or health conditions. The CDC officially recommends using WHO curves for children 0-24 months (in the US) and its own curves from age 2 onward.
The most visible practical difference shows up in early weight gain: breastfed babies, the WHO sample's standard, tend to gain weight faster in the first 2-3 months and then slow down, compared with formula-fed babies, more present in the CDC's historical sample, collected in national surveys between 1963 and 1994. Using the wrong chart at this stage can make a healthy breastfed baby look "too slow" with no real cause.

When to use each one

8-month-old baby

Input: Peso-para-idade, comprimento-para-idade
Expected output: Use as curvas da OMS (0-24 meses)

This is the range covered by this calculator.

6-year-old child

Input: IMC-para-idade
Expected output: Use as curvas do CDC (2-19 anos)

Available in the Child and Teen BMI Calculator in the catalog.

Full tool FAQ

What does it mean that my baby is in the 60th percentile?

It means that, among 100 babies of the same sex and age in the WHO reference population, about 60 have a value equal to or lower, and 40 have a higher value. It is not a score from 0 to 100: a baby in the 15th percentile can be perfectly healthy, just smaller than most babies of the same age.

Is a low or high percentile a reason for concern?

Why does the WHO use different curves than the US CDC?

What is the z-score and why does it show up in the result?

Does this calculator compute the baby's BMI?

Why does the calculator ask for age in months and days, instead of the birth date?

Is the data I enter saved anywhere?

Does this calculator replace well-child visits?

Frequently asked questions

Can a Brazilian baby be compared to the WHO curves?

Yes. The multicenter study that produced the WHO curves included Brazilian children (Pelotas, RS) among the six data-collection countries, alongside Ghana, India, Norway, Oman and the United States.

Why is there no BMI chart for babies 0-24 months?

The WHO recommends evaluating weight, length and weight-for-length separately at this age, rather than BMI, which only becomes the standard reference metric from age 2, when the CDC BMI-for-age curve takes over.

Is a clinic that only has the CDC chart wrong when assessing a 6-month-old?

Not necessarily wrong, but less precise: comparing a breastfed baby against the CDC's historical American reference, which mixes feeding patterns, can produce a biased percentile reading in the early months. The official recommendation, from both the WHO and the CDC itself in the US, is to use the WHO chart up to 24 months.

Do the charts differ between boys and girls?

Yes. Boys and girls have different growth rates and body composition from birth, so both the WHO and the CDC publish separate charts for each sex. Comparing a baby's measurement against the wrong sex's chart distorts the calculated percentile.

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who vs cdc growth charts difference

WHO or CDC Growth Charts: Which One Should You Use?

Both charts measure the same things, weight, length/height, head circumference, but they were built with different purposes, which is why each is recommended for a different age range.

Prescriptive standard vs. descriptive reference

The WHO curves (2006) are a "standard": they describe how children grow under environmental conditions considered ideal (predominantly breastfed, no maternal smoking, good socioeconomic conditions), based on data from over 8,000 children across six countries.

The CDC curves are a "reference": they statistically describe how American children actually grew in historical national surveys, without filtering for ideal feeding or health conditions. The CDC officially recommends using WHO curves for children 0-24 months (in the US) and its own curves from age 2 onward.

The most visible practical difference shows up in early weight gain: breastfed babies, the WHO sample's standard, tend to gain weight faster in the first 2-3 months and then slow down, compared with formula-fed babies, more present in the CDC's historical sample, collected in national surveys between 1963 and 1994. Using the wrong chart at this stage can make a healthy breastfed baby look "too slow" with no real cause.

Full tool FAQ

What does it mean that my baby is in the 60th percentile?

Is a low or high percentile a reason for concern?

Why does the WHO use different curves than the US CDC?

What is the z-score and why does it show up in the result?

Does this calculator compute the baby's BMI?

Why does the calculator ask for age in months and days, instead of the birth date?

Is the data I enter saved anywhere?

Does this calculator replace well-child visits?

Frequently asked questions

Can a Brazilian baby be compared to the WHO curves?

Yes. The multicenter study that produced the WHO curves included Brazilian children (Pelotas, RS) among the six data-collection countries, alongside Ghana, India, Norway, Oman and the United States.