## 4 Discussion
The distribution of birth quartiles by age group among juniors revealed similar trends in the 13- and 14-year-old subgroups, showing a pattern of Q2 > Q1 > Q3 > Q4, with a modest predominance of Q1 and Q2 births. This pattern shifted in the 15-year-old subgroup, where gymnasts born in Q3 significantly dominated (Q3 > Q2 > Q1 > Q4). [PERSON] et al. [49] also found that, among RGs aged 7-14, those born in Q1 and Q2 were more frequent than those born in Q3 and Q4, although statistical significance was not evaluated. Conversely, [PERSON] et al. [50] found evidence of a standard RAE favoring relatively older gymnasts (under 15) and a reverse RAE favoring relatively younger gymnasts (over 15) in Canadian national-level artistic gymnastics. [PERSON] et al. [51] suggested that in recreational esthetic sports, relatively older girls born in Q1 and Q2 may be at greater risk of dropping out, possibly due to early pubertal development, which has been associated with adverse psychosocial outcomes and lower levels of physical activity [52]. In the current study, no evidence of the RAE was found in the senior individual, senior group, or senior total categories, which is consistent with findings from another international study on senior female artistic gymnasts [53]. However, a separate analysis of senior individual RGs across continental championships during one Olympic cycle showed a notable difference in chronological age, with a gap of up to 2.3 years between the median ages of American and African athletes [54]. The analysis of birth quartile distributions by performance level revealed a significant over-representation of RGs born in Q3 and an under-representation of those born in Q4 among the overall sample of finalists, as well as within the subgroups of group finalists and junior group finalists. Similar deviations were also observed among all junior finalists, with a notable under-representation of gymnasts born in Q4. In contrast, no evidence of the RAE was found among individual finalists, senior finalists (across all categories), or N-Fs. Performance-level analysis further confirmed that the trends seen in the qualification stage--favoring Q3 and disfavoring Q4--persisted among finalists. Moreover, effect sizes for the observed differences increased from small to medium in both the group finalists and junior group finalists categories, suggesting a stronger influence of this atypical RAE pattern at higher levels of competition. These findings point to the potential impact of relative age on competitive success in rhythmic gymnastics. On the other hand, the absence of significant birthdate distribution differences among junior individual finalists aligns with the findings of [PERSON] et al. [37], who reported no RAE-related differences in performance scores among participants in the first junior WCH in 2019. The significant under-representation of Q4-born athletes in the entire sample of finalists may be explained by early deselection of relatively younger gymnasts--those born at the end of the calendar year--during initial stages of the athlete development pathway. This trend is also reflected in the broader patterns observed among overall group RGs and the junior total sample during the qualification stage. [PERSON] et al. [55] similarly documented systemic bias against athletes born later in the calendar year across both physically demanding and cognitive/skill-based sports. The exclusion of relatively younger junior gymnasts at early stages--and their under-representation among 2023 WCH finalists--highlights a potential concern for coaches. Talented RGs born in Q4 may not receive equal training opportunities, which could hinder their long-term development and competitive progression [56]. Less mature athletes may miss out on critical development opportunities if excluded from elite pathways. It is essential that coaches and organizations recognize the RAE and adapt their selection processes to ensure equal opportunities for all athletes, regardless of their chronological age or biological maturity.