Length (for babies who lie down) or height (once standing) is tracked on a WHO height-for-age chart the same way weight is — as a percentile against healthy same-age, same-sex children. Most babies sit somewhere between the 3rd and 97th percentile, and all of that is normal.
The growth pattern to expect
Babies typically grow fastest in the first year — around 25 cm (10 in) between birth and their first birthday — then slow to roughly 12 cm (5 in) in the second year. That slowing is expected, not a problem, and the WHO curves are built to show it.
Percentile is not "small" or "tall"
A baby at the 5th percentile is simply smaller than 95% of peers the same age and sex — not abnormal. Growth is more like following a lane than winning a race. Pediatricians worry less about the lane you're in and more about sudden changes across lanes without a clear reason.
When a single reading deserves a second look
Steady tracking along a percentile is reassuring even at the extremes. A sharp drop across percentile lines (for example from the 40th to the 5th within a few months) is the pattern that triggers a pediatrician visit. Measured with the same device and technique each time, your curve becomes far more trustworthy than any single dot.
Let the chart do the math
GrowChart plots length and height on the official WHO curves, computes the exact percentile, and shows you the trend over time — the same method your pediatrician's chart uses. Start a free chart for your baby.
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