Backgrund Unintentional injuries among children and adolescents are common and remain a public health problem. Few studies have described the epidemiology and the changes of the frequency of unintentional injuries in different age groups. Understanding injury pattern for children in all stages of development is important when planning appropriate prevention actions. No previous large longitudinal study has described age-related tendencies in unintentional pediatric injuries.

Objective To describes the age-related trends in unintentional injuries in children and adolescents in an urban population.

Methods A retrospective study of all children and adolescents aged 0–17 years treated for unintentional injuries at Odense University Hospital, Denmark 1980–2021. Information about age, gender, place of injury, and diagnoses were extracted from the emergency department register. We estimated gender specific annual incidence rates (IRs) in different age groups (0–4, 5–9, 10–14, and 15–17 years). The severity was classified by mild or severe injuries.

Results Overall, 292,737 unintentionally injured children and adolescents were included. The median age was 10 years and 57.4% were boys. The overall IR was 241 (CI: 240–242) for boys and 188 (CI: 187–188) for girls per 1000 population/years. In the study period, the overall incidence decreased by 44% in boys and by 38% in girls. The overall IR for severe injuries did not change in the study period, whereas the IR of mild injuries decreased significantly in all age groups in both gender. The upper limbs were most frequently injured in all age groups for both gender, except for children aged 0–4 years, where lesions mostly occurred in the head or neck. In the youngest age groups 0–4 years and 5–9 years wounds were the most common type of lesion, while bruises were the most common type of lesion in the oldest age groups. Fractures accounted for 14.5% of the lesions with the highest proportions in the 5–9 years and 10–14 years age group.

Conclusions The study provides age- and gender-stratified IRs, which can serve as a baseline for comparing IRs in different countries and for monitoring trends in injury frequency. The IRs varied with gender and age.