Trends and disparities in unintentional injury mortality among children under five in northern Iran: a 10-year population-based surveillance study (2013-2022).

Although unintentional injuries (UIs) are a well-recognized cause of early childhood mortality, regional evidence on their trends and disparities remains limited in Northern Iran, where subnational variation may obscure national progress. This study investigates the patterns and characteristics of unintentional injury deaths (UIDs) in this vulnerable population. We conducted a retrospective trend study using mortality data from the under-five death (U5D) surveillance system in Northern Iran, covering the years 2013 to 2022. Causes of death were classified according to ICD-10 codes. Temporal trends in UIDs were examined using Join point regression analysis, while Poisson regression was applied to estimate relative risks (RRs) and 95% confidence intervals (CIs) for sex- and residence-based disparities. Among 3390 U5Ds, 240 (7.08%) were attributable to UIs. The overall unintentional injury death (UIDs) rate was 0.81 per 1,000 live births, declining non-significantly from 0.93 in 2013 to 0.52 in 2022 (APC - 3.34%, p = 0.162). Transport accidents were the predominant cause (56.7%), followed by accidental drowning and submersion (10.8%) and other accidental threats to breathing (10.0%). Girls had a significantly lower risk of UIDs rate compared to boys (RR = 0.76; 95% CI: 0.58-0.98). No statistically significant difference was found between rural and urban areas (RR = 1.25; 95% CI: 0.97-1.61). Between 2013 and 2022, UIDs among children under five in Mazandaran Province showed a downward trend; however, the reduction was not statistically significant. During this period, boys consistently exhibited a significantly higher risk of injury-related mortality compared with girls. These patterns underscore persistent inequities in child injury outcomes and highlight the need for sustained, equity-focused preventive strategies, particularly those targeting high-risk groups and the leading mechanisms of injury, such as transport incidents, drowning, and suffocation.