Purpose: The sex ratio at birth (SRB) is a biological indicator known to fluctuate under societal stressors. This study evaluated temporal changes in South Korea's SRB during the coronavirus disease 2019 (COVID-19) pandemic, exploring whether the timing of the shift aligned with periconceptional influences (e.g., severe stress impacting paternal sperm viability), with particular focus on Daegu, the initial epicenter of the outbreak. Materials and Methods: We conducted a retrospective population-based analysis using national registry data for all live births from January 2015 to December 2022. SRB was compared between pre-pandemic (2015-2019) and pandemic (2020-2022) periods. Interrupted time series analysis and baseline-derived 95% prediction intervals were employed to identify longitudinal shifts and month-specific anomalies. Results: Nationwide SRB significantly decreased from 105.48 (pre-pandemic) to 104.87 (pandemic) (p=0.032). In Daegu, SRB decreased to 98.2 in November 2020, nine months after the peak infection wave (February-March 2020), coinciding with a sharp reduction in total births. Additionally, SRB suppression was observed in early 2022, corresponding to conceptions during the prolonged phases of the pandemic. Conclusions: The COVID-19 pandemic was associated with a significant SRB decline in South Korea. The nine-month lag observed in the Daegu epicenter aligns with a pre-fertilization mechanism, consistent with the exploratory hypothesis that acute societal stress may disproportionately impair Y-bearing sperm viability. These hypothesis-generating findings suggest SRB serves as a sensitive-level indicator of societal distress.
PURPOSE:To characterize nationwide patterns of initial prostate cancer (PCa) management in Korea from 2010 to 2020, stratified by clinical stage, risk, and residential context. MATERIALS AND METHODS:We performed a secondary analysis of a chart-abstracted cohort from 51 general hospitals. Initial treatment was classified into ten mutually exclusive categories (active surveillance; surgery; surgery after androgen deprivation therapy [ADT]; radiotherapy; radiotherapy after ADT; docetaxel after ADT; androgen receptor-targeted agent [ARTA] after ADT; ADT-only ≥1 year; other active treatment; unknown). Localized disease (T1-T4N0M0) was stratified by risk (low, intermediate, and high). Residential context was coded as capital versus non-capital and urban versus rural. National Comprehensive Cancer Network risk stratification (version 2.2024) was applied uniformly across survey years. RESULTS:Among 27,075 men, initial management differed significantly by stage, risk, and residence. In localized disease, surgery predominated, active surveillance was most frequent in low-risk disease, and radiotherapy and ADT-only increased with higher risk (p<0.001). Over time, ADT-only decreased in metastatic disease, with increases in radiotherapy and systemic intensification (p=0.004). Capital and urban residence were associated with greater use of surgery in localized disease and systemic intensification in metastatic disease, whereas non-capital and rural residence relied more on ADT-only (all p<0.001). In multivariable analyses, residential context remained independently associated with treatment selection after adjustment for age, prostate-specific antigen, grade, and stage. CONCLUSIONS:Initial PCa management in Korea during the 2010s reflected contemporary adoption of surgical and systemic therapies but demonstrated persistent geographic variation, indicating residential context influences real-world access to guideline-concordant care.
