How to read this
A percentile says where your baby sits in a crowd of 100 babies the same age and sex. The 67th percentile means 66 of them weigh a bit less and 33 weigh a bit more. That's all it means.
Two things matter far more than the number itself:
- The trend. A baby who's tracked the 30th percentile since birth is doing great. One who drops from the 75th to the 25th in a month is worth a call.
- The whole baby. Feeding well, peeing, pooping, hitting milestones — those count for far more than a dot on a chart.
Where the data comes from
Every percentile here is computed straight from the WHO Child Growth Standards — the World Health Organization's international standard for healthy growth, weight-for-age, boys and girls from 0 to 5 years.
When to call your pediatrician
Numbers are useful, but parents are better instruments than charts. Call if you see fewer than 4–6 wet diapers a day, a sudden drop across two percentile lines, lethargy, or feeding that suddenly gets harder. You're not bothering anyone.
Frequently asked
My baby dropped from the 60th to the 40th — is that bad?
Almost always: no. Percentiles drift in the first 18 months as breastfed and formula-fed babies diverge from the chart. What matters is whether your baby is still gaining steadily, feeding well, and behaving like themselves. Bring it up at your next visit, but a single shift across one line is not an emergency.
What's a healthy percentile?
There isn't one. The 3rd percentile and the 97th are both perfectly healthy — they describe size, not health. A baby tracking steadily along the 10th is thriving; so is one along the 90th. Pediatricians watch the pattern over time, not the number on any single day.
My twins have different percentiles — should I worry?
Usually not. Twins are often born smaller and can sit lower on the chart for months — and even identical twins end up different sizes. Each baby is compared against the same single-baby WHO standard, so a gap between siblings is expected. Watch that each one is gaining steadily along their own line.
Log weights, get the curve drawn for you, and hand your pediatrician a clean PDF at the next visit.
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