Study of variations in semen quality in men from 12 geographical locations in Spain.

Objective: This study aimed to evaluate possible variations in semen quality among patients undergoing fertility evaluation in 12 different geographical locations in Spain.

Methods: The study was conducted in 12 assisted reproduction centers located in different regions of Spain. Semen samples from 2,336 men seeking fertility assessment were analyzed. Seminal parameters-including semen volume, sperm concentration, motility, morphology, vitality, and total motile sperm count (TMS) were compared by geographic location. All parameters were evaluated using standardized methodologies, with interlaboratory quality controls to ensure consistency.

Results: No significant differences in patient age were found between centers (ANOVA, p > 0.05). However, statistically significant variations in semen volume, sperm concentration, total motility, and TMS were observed between the centers (p = 0.020, 0.004, 0.000, and 0.008, respectively). Men from Asturias exhibited the highest values for sperm concentration (mean: 59.8 ± 48.7 × 10 sperm/mL), motility (mean total motility: 54.3 ± 20.7%), and TMS (mean: 101.2 ± 107.5 × 10^6), with statistically significant differences compared to other regions. Patients from Cataluña, Almería, and Málaga followed in these metrics. In contrast, men from Granada presented the lowest sperm concentration and TMS (mean concentration: 43.1 ± 35.8 × 10^6 sperm/mL; mean TMS: 43.1 ± 34.6 × 10^6), followed by individuals from Alicante and Madrid. No significant differences in sperm morphology or vitality were observed between centers.

Conclusion: Since all seminal parameters were assessed using standardized methodologies, the observed differences in semen quality between regions are unlikely to be due to laboratory variability.