Age relative to school class peers and emotional well-being in 10-year-olds.

Purpose: The aim of this study was to investigate the effect of age relative to school (i.e., class or grade level) peers on emotional well-being and the role of possible mediators of this effect in early adolescence using a large set of individual-level data from a community survey. Methods: A large community-based survey of 10-year-old children and their primary parents was conducted in Tokyo, where the school entry cutoff date is fixed. Emotional well-being was assessed by the WHO (Five) Well-Being Index (WHO-5). Academic performance and the experience of being bullied at school were also evaluated as potential mediators of the effect of relative age. Results: A total of 4,478 children participated in the study. In a univariate linear regression analysis, the relative birthdate (continuous variable starting from the school entry date and ending at the last date of the academic grade) was negatively associated with emotional well-being (β = -0.043, p = .005). The path analyses suggested that academic performance and bullying mediated the relationship between the relative birthdate and emotional well-being (both p < .01). Conclusions: Among a sample of 10-year-olds, children who were younger compared to class peers had lower levels of emotional well-being. Academic performance and victimization by peers mediated the relationship. [ABSTRACT FROM AUTHOR]