Background: There is growing interest in the potential impact of the physical environment on human fertility. This study aimed to explore the association between built environment and semen parameters among men who sought fertility evaluation .
Methods: This is a cross-sectional study involving 5,886 men living in the Seoul Capital Area whose semen was tested at a single fertility center during 2016–2018. Environmental exposures evaluated were distance to fresh water (river and lake), the coast, major roadways, and neighborhood greenness measured by Normalized Difference Vegetation Index (NDVI). Outcome indicators were semen volume, sperm concentration, percentage of progressive motility, vitality, normal morphology, and total motile sperm count. We used linear regression to model standardized values of six semen quality indicators.
Results: Majority of the study population (mean age 39 years) were white-collar workers, clerks, and service workers. None of the mean values of semen quality indicators showed linear trends across quartiles of built environment components. Linear associations between built environment features and semen quality indicators were not evident except for NDVI within 500 m and sperm vitality (β = 0.05 per 0.1-increase; 95% confidence interval (CI): 0.01, 0.09). The 2nd quartile of distance to fresh water was associated with lower progressive motility compared to the 1st quartile (β = −0.10; 95% CI: −0.17, −0.03). Proportion of vitality was higher among men in the 2nd quartile of distance to roadways than those in the 1st quartile (0.08; 95% CI: 0.01, 0.15). Men in the 2nd quartile of NDVI showed higher total motile sperm count than those in the 1st quartile (0.09; 95% CI: 0.01, 0.17). In multi-exposure model, the positive association between NDVI and vitality remained (0.03, 95% CI: 0.00, 0.06).
Conclusions: This study contributes potential evidence regarding the impact of built environment on male fertility ; specifically, a positive association between residential greenness and percentage of sperm vitality among Korean men with a history of infertility .
