Quantitative effects of male age on sperm motion.

Background: Semen quality is associated with fertility status, but there is little quantitative information on risk factors that affect semen quality, especially in non-clinical populations. Advancing male age has been associated with a decline in semen quality, with the largest effect being on sperm motility. However, there is little quantitative data on the specific components of sperm motion that are affected by male age.

Methods: We performed linear regression analyses of 14 aspects of semen quality measured by computer-assisted semen analysis (CASA) in a non-clinical cohort of 90 non-smoking men, aged 22-80 years, who had no history of infertility or reproductive problems.

Results: We found age-associated declines in CASA-determined motility (% motile, 0.8% per year; % progressively motile, 0.9% per year; % rapidly motile, 0.4% per year, P
Conclusions: Quantitative analysis of sperm motion indicates that as men age, they produce fewer motile sperm, which are able to travel less along a linear path, thus covering less forward distance per unit time. These findings may have fertility implications for men who choose to delay fatherhood.