Relationship between male aging and semen quality: a retrospective study on over 2500 men

Abstract

Purpose: We aimed to evaluate whether and to what extent an association exists between male aging and worsening of semen parameters and to determine whether a threshold age can be identified above which the decline in semen quality becomes statistically significant.

Methods: 2612 men (age: 16-56 years) attending an andrology outpatient clinic for semen analysis and clinical evaluation were studied. Semen analyses were performed according to the ongoing WHO-recommended procedures. Total motile count (TMC) and total progressive motile count (TPMC) were calculated by multiplying total sperm number by total motility and progressive motility, respectively.

Results: Significant negative correlations were found between age and total motility (r = - 0.131, p < 0.0001), progressive motility (r = - 0.112, p < 0.0001), TPMC (r = - 0.042, p = 0.037), and normal sperm morphology (r = - 0.053, p = 0.007). All these associations persisted in multivariate regression models adjusted for abstinence time, smoking, history of male accessory gland infections, varicocele and the year in which semen analysis was performed. When comparisons were performed among quartiles of increasing age, the fourth quartile, corresponding to the age group > 40 years, was associated with a significant decrease in total and progressive motility. An earlier decline in the TPMC and percentage of normal forms was also observed.

Conclusion: Advancing male age exhibits an independent association with a decrease in the percentage of motile and morphologically normal spermatozoa, with greater evidence from the age of > 40 years. Further studies are warranted to elucidate the mechanisms and clinical reflections of these associations.

Keywords: Ageing; Infertility; Oxidative stress; Sperm morphology; Sperm motility; Spermatozoa.

Fig. 1

Study flow-chart

Fig. 2

Correlations between age and semen volume (A), sperm concentration (B), total sperm number (C), TMC (D), total motility (E), progressive motility (F), TPMC (G), and normal sperm morphology (H). Spearman’s rank correlation coefficients, and p values are shown. Abbreviations: TMC, total motile count; TPMC, total progressive motile count

Fig. 3

Distributions of values for total motility (A), progressive motility (B), total progressive motile count (TPMC) (C), and normal sperm morphology (D) among quartiles of increasing age. Values are medians (horizontal bars) with 25th and 75th centiles (boxes); the “whiskers” extend out to the minimum and maximum value. *p < 0.008 vs all the others; ^†p = 0.006 vs quartile II; ^§p < 0.008 vs quartile II and III. Based on the number of comparisons, significance was accepted for p < 0.0083