A baby born early was never supposed to match a full-term curve in the first weeks. The Fenton chart gives preterm babies their own growth reference, plotted by how far along they would have been.
Why a separate chart
Standard WHO curves assume a baby born at term. A baby born at 32 weeks is on a different trajectory, so pediatricians use the Fenton reference, which plots growth by postmenstrual age instead of birthday age.
Catch-up growth, in its own time
Most preterm babies show catch-up growth in the first year or two — moving up across percentile lines as they recover the ground lost early. The pace varies a lot, and the Fenton curve is the honest yardstick for that journey.
Corrected age matters
Pediatricians often use corrected age — the age the baby would be if born on time — for the first two years. GrowChart tracks gestational weeks and applies corrected age automatically so the chart matches clinical practice.
The right chart, automatically
GrowChart uses the Fenton reference for preterm babies and the WHO curves for term babies, and switches as the child grows into the standard charts.
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