Age- and sex-specific patterns, seasonality and temporal trends of acute pediatric fracture admissions in China: a pooled multicenter hospital-based cohort of 6206 children

Background Childhood fractures are a major source of pediatric morbidity and hospital use, yet contemporary large-scale Chinese data with denominator-based modeling and age- and sex-specific analysis remain limited. We characterized the anatomical, seasonal and developmental epidemiology of acute pediatric fracture admissions in a pooled hospital-based cohort. Methods In this retrospective study, children (< 18 years) with a confirmed acute fracture admitted to three Chinese hospitals between October 2020 and November 2024 were identified from pooled electronic medical records by text mining of structured diagnoses; pathological and old fractures were excluded. Descriptive and regression analyses were patient-level (earliest acute admission per child); seasonality and secular trend in the fracture-admission rate, with all pediatric admissions as the denominator, were modeled at the episode level with cosinor negative-binomial regression. Multivariable logistic regression examined factors associated with multiple-region fracture and with lower-only (vs. upper-only) limb fracture, including the age-by-sex interaction and sex-specific site predilection. Results Among 251,385 pediatric admissions, 7,142 (2.84%) were acute-fracture admissions in 6,206 children (70.9% male; male: female 2.44:1; mean age 9.7 ± 4.8 years). The upper limb was most often involved (48.9%), led by the humerus (21.6%) and forearm (15.6%); supracondylar humeral fractures comprised 9.7%. The fracture-admission rate showed autumn-peaking seasonality (negative-binomial peak-to-trough ratio 1.31, 95% CI 1.14–1.55; peak in mid-October; p = 0.007) and a declining fracture-admission rate relative to all pediatric admissions (rate ratio 0.82 per year, 95% CI 0.78–0.86). Lower-only (vs. upper-only) limb fracture rose with age (12–17 vs. 6–11 years: OR 2.30, 95% CI 2.00–2.65) and was less frequent in boys (OR 0.58, 95% CI 0.50–0.66); the sex effect varied with age (interaction p < 0.001). Site predilection was sex-specific (boys: forearm, hand; girls: ankle, foot, spine, pelvis, patella, tibia/fibula). Estimates were robust to the unit of analysis, limb coding, data-source stratum and denominator composition. Conclusions In this hospital-based cohort, acute pediatric fracture admissions showed male and upper-limb predominance, an autumn peak, an age-dependent shift toward lower-limb injury, sex-specific site predilection and a declining share of pediatric admissions over time. Because injury mechanism, activity and a defined source population were unavailable, these patterns describe the hospital admission burden and generate hypotheses for age-, sex- and season-informed prevention research and trauma-service planning rather than establishing specific interventions.