BackgroundPhysical abuse is a major public health concern and a leading cause of morbidity and mortality in infants. Clinical decision tools derived from trauma registries can facilitate timely risk-stratification. The Trauma Quality Improvement Program (TQIP) database does not report age for children <1 year who are at highest risk for abuse. We report a method to capture these infants despite the missing age. MethodsPatients ≤17 years were identified from TQIP (2017–2019). The primary outcomes included injuries resulting from confirmed or suspected child abuse captured by diagnosis codes or report/investigation of physical abuse, or different caregiver at discharge available in TQIP. We used two methods to select infants within TQIP. In the first, World Health Organization (WHO) growth standards for stature or length-for-age and weight-for-age were selected to capture children younger than 1 year. In the second, a K-means machine learning algorithm was used to cluster patients by weight and height. We compared outcome and injury data with and without patients <1 year. ResultsUsing the WHO growth standard 19,916 children <1 year were identified. A total of 20,513 patients had a report of physical abuse filed, and 9393 were infants <1 year. Increased age-adjusted odds ratios [95% CI] were seen for fractures of the upper limb (1.28 [1.22–1.34]), vertebrae (1.89 [1.68–2.13]), ribs (5.2 [4.8–5.63]), and spinal cord (3.39 [2.85–4.02]) and head injuries (1.55 [1.5–1.6]) with infants included. ConclusionsIn a nationwide trauma registry, WHO growth standards can be used to capture patients under one year who are more adversely impacted by maltreatment. Type of StudyRetrospective, Cross-sectional. Level of EvidenceLevel III, Diagnostic.