The effect of aging on semen parameters in normozoospermic men: A cross-sectional study

Abstract Background Semen parameters change with age and are reported differently worldwide. Objective This retrospective cross-sectional study aimed to investigate the semen quality pattern among aging men and the age thresholds for semen parameters. Materials and Methods The records of men who had normal semen parameters from January 2015-June 2020 were retrospectively evaluated for andrological outpatient at Samsun Training and Research hospital and Gazi hospital in Samsun, Turkey. Adult men meeting the inclusion criteria were divided into 3 groups of I) 18-29 yr (n = 629), II) 30-39 yr (n = 775), and III) 40-49 yr (n = 190). Correlations between age and sperm parameters were then analyzed. Results A total of 1594 men were enrolled in the study. Significant differences were observed in total sperm numbers, total motility rates, progressive motility rates, nonprogressive motility rates, normal morphology rates, mean semen volume, and sperm concentrations. The parameters of total sperm number, progressive motility rate, and normal morphology rate were significantly higher in group I than in the other 2 groups (p < 0.001, p < 0.001, and p < 0.001, respectively) and in group II compared to group III (p = 0.001, p = 0.003, and p < 0.001), respectively. Mean semen volume and total motility rate were significantly higher in group I than in the other groups (p = 0.001 and p < 0.001, respectively). However, no difference was observed between group II and group III (p = 0.61 and p = 0.04, respectively). Conclusion Age has a significant impact on semen parameters capable of affecting male fertility, particularly total sperm numbers, the progressive motility rate, and the normal morphology rate.


Introduction
Aging is an inescapable process resulting in various physiological changes. Individuals get married and plan to have children later in life, including their career, education, and economic and social factors (1). Various changes can occur in semen parameters with aging, for reasons such as stress, an unhealthy diet, decreased physical activity, chemical additives, psychological factors, and exposure of the scrotum to radiation in association with frequent use of technological devices, including laptop computers and cell phones (2)(3)(4).
Semen analysis is the first laboratory test performed for evaluating male fertility capacity.
Research into the impact of paternal age on semen parameters is still inconclusive.

Materials and Methods
Semen analysis results for men presenting to departments for andrological outpatients at the Samsun Training and Research hospital and Gazi hospital in Samsun, Turkey due to infertility between January 2015 and June 2020 were evaluated in this retrospective cross-sectional study.

Participants and evaluation
The study included 1594 men with normal semen analysis results presenting due to infertility. These were divided into 3 groups based on age: group I) 18

Statistical analysis
Data analysis was performed using SPSS

Results
The study was conducted with 1594 participants with a mean age of 32 yr (IQR: As shown in table I, total sperm numbers,   progressive  motility  rates,  and  normal morphology rates also differed significantly between the groups (p < 0.001). All 3 parameters were significantly higher in group I than in groups II and III ( Figure 1). The highest sperm concentration value was observed in group I, and the highest nonprogressive motility rate in group III, being both elevations statistically significant (Table I). Intergroup analysis revealed a significant difference only between groups I and III, other differences being insignificant.

Discussion
The present study involved the analysis of an and sperm morphology (8,12). In one such study, the probability of a decreased sperm count was 2.92-fold greater among men aged between 41-50 compared to those aged between 21-30 yr, while men aged > 50 were 11.91 times more likely to exhibit impaired sperm progressive motility than men aged between 21-30 (8).
Similar to the present research, another study divided the participants into 3 age groups and also reported significant decreases in progressive motility and sperm morphology (17).
In contrast to the present study; however, those authors reported similar total sperm numbers between the age groups 29-39 and 40 or higher, while numbers in the 18-28 age groups were significantly higher. Interestingly, the total sperm count in the age group 29-39 was lower than those in their 40 and over, although the difference was not statistically significant (17). A separate piece of research noted that progressive motility began decreasing significantly from the age of 28, and total sperm numbers from the age of 42 (7). However, in contrast to these studies and the present research, other authors have observed no difference in total sperm count, sperm morphology, or total motile count between men under and over 40 (18).
Although most studies have reported an inverse correlation between age and semen volume, there is still no consensus on this subject.
In one extensive study, the researchers observed that semen volume diminished with age, and that the risk of decreased semen volumes increased by 1.06-fold compared to the previous year (8). 2 other studies reported significant age-dependent decreases in semen volume (12,18). In contrast, other authors have reported no correlation between age and semen volume (7,17,19).
However, semen volume was significantly higher Aging and semen quality alcoholism are now required to confirm these findings.

Conclusion
Age is negatively correlated with semen parameters, especially total sperm number, progressive motility rate, and normal morphology rate, in normozoospermic men with no testis alterations capable of impairing semen parameters. It should not be forgotten that while semen parameters are not absolute evidence of male fertility potential, they nevertheless decrease with age, and the age factor should be considered in the treatment of infertile couples.