Interface-Based Validation of a Pediatric Growth Monitoring Application “WeGrow-Health” against WHO and CDC References

Background: Growth apps convert measurements into z-scores and nutritional labels, but their calculations are rarely checked against official software. Objective: To validate, through the user interface alone, the z-scores, labels and implausible-value flags of the WeGrow-Health web application against WHO and CDC 2000 references. Methods: In a prespecified agreement study, 841 synthetic measurements (600 realistic profiles aged 2 days to 19 years plus engineered cutoff, extreme, age-transition and flag-limit cases) were entered by batch upload and manual entry. App exports were compared with full-precision values from the WHO packages anthro and anthroplus, the CDC package cdcanthro and the CDC 2000 LMS tables. Differences of 0.006 SD or less were attributed to display rounding. Invalid inputs were tested through the batch upload. Results: All 6,737 z-scores across 8 WHO and 5 CDC indicators agreed within the 0.006 SD rounding tolerance (maximum difference 0.0051 SD), and the upper 95% bound for differences above 0.10 SD was 0.08%. No z-score was reported outside a valid age range or omitted within it. All 10 status labels agreed with the reference categories, including 50 classification decisions within 0.005 SD of a cutoff, and flags matched WHO (52 of 52) and CDC (50 of 50) rules. Extended CDC BMI metrics matched cdcanthro. Impossible dates and values were rejected, and decimal commas were parsed correctly. Conclusions: WeGrow-Health reproduced WHO and CDC 2000 growth calculations to display precision, supporting worldwide use of the app by child health professionals, researchers, caregivers, schools, clinics, hospitals and health organizations.