Introduction
Infertility remains a significant global public health problem and an important clinical issue affecting 15% of couples of reproductive ages [1]. The incidence of male infertility is quite high [2]. Infertility related to the so-called male factor is defined as an alteration in sperm concentration, motility, and morphology in at least one of two semen analyses taken 1 to 4 weeks apart [3-4]. In humans, infertility is the cause in 40-50% of cases and affects approximately 7% of men. Male infertility sometimes arises from abnormalities in sperm, and sperm quality is used as an indirect indicator of male fertility [5-7]. In recent decades, numerous researchers have shown a global decline in human sperm quality [8]. Numerous factors, both hereditary and environmental, can influence infertility rates [9]. Male factors contribute to infertility in 50% of couples worldwide [10]. Approximately 30-50% of cases of male infertility are classified as idiopathic [11]. Various idiopathic factors, including smoking, alcohol consumption, drug use, obesity, psychological stress, older age, nutritional factors, exposure to environmental or occupational toxins, diet, physical activity, carrying a mobile phone in a trouser pocket, and sleep duration, have been identified as potential risk factors for reduced semen quality [12-15]. The latter decreases the likelihood of egg fertilization, thereby affecting the success of conception [16]. Untreated male infertility increases the likelihood of further systemic consequences such as cardiovascular, urogenital, and metabolic diseases, as well as cancer. These conditions collectively affect the quality of life of those affected [17]. Regarding male age and fertility, some data link decreased fertility potential to older age, which is supported by the results of assisted reproductive technologies [18-20].
Nevertheless, further consensus is needed regarding the impact of male aging on sperm quality. While some studies have shown a correlation between male aging and sperm quality, other studies have not found such a link [21-24]. Several studies have investigated the impact of certain clinical and lifestyle factors, including obesity, alcohol consumption, and smoking, on sperm parameters. The prevalence of obesity is a growing public health concern. The American Medical Association recently defined obesity as a disease [25]. While the main focus in studying the negative consequences of obesity is on overall health, available data suggest that reproductive health is also affected. Several studies have shown that an increased body mass index (BMI) in men may lead to decreased sperm production [26-27].
Conversely, other studies have not found a correlation between male body mass index (BMI) and sperm characteristics [28-29]. Moreover, the relationship between body size and sperm quality after weight loss further complicates our understanding of this issue. Some studies have shown a decrease in sperm production associated with significant weight loss, while others have observed an improvement in sperm characteristics [27,30-31]. However, both alcohol consumption and smoking are thought to have detrimental effects on male fertility and, consequently, on reproductive outcome [32]. Nevertheless, the impact of these factors on standard sperm characteristics is still a subject of debate [33-36].
As a matter of fact, a comprehensive study of the impact of excessively high BMI, alcohol consumption, and smoking on the decline in sperm quality with age has not yet been conducted. Furthermore, it is crucial to consider the significant influence of concomitant systemic diseases on infertility and sperm quality. The complexity of identifying the underlying causes of male subfertility and infertility significantly limits treatment and intervention options. The undeniable influence of sociodemographic factors on both the general health of men and their reproductive health is evident [37-41]. The goal of this descriptive cross-sectional study was to investigate the correlation between various demographic and lifestyle characteristics and standard sperm parameters to determine the impact of lifestyle and demographic factors on sperm function. Hence, we aimed at assessing the influence of age, clinical conditions, and lifestyle on semen samples from patients attending an andrology laboratory, in accordance with World Health Organization (WHO) recommendations. The study was conducted under controlled conditions, using the same operators, equipment, and laboratory procedures, adhering to strict quality standards.
Material and methods
Study population
The study initially included men under 40 years of age who underwent semen analysis at the andrology laboratory from October 2022 to August 2023. All participants provided written informed consent. Individuals with pre-existing andrological and systemic diseases known to contribute to poor sperm quality were excluded from the study based on specific criteria in effect at that time. A total of 200 men seeking infertility treatment were included in the study. Table 1 presents the main characteristics of the men referred to the Center for Infertility Treatment. The mean age of the participants (±standard deviation) was 34.9±5.9 years (range: 23-52 years). The majority of participants were non-smokers (66.0%), urban residents (73.5%), had a normal weight (46.97%), primary education (73.74%), low physical activity (72.5%), and low income (48.24%).
Table 1. Baseline characteristics of men referred to Urmia University of medical sciences Infertility center
|
Variables |
Category |
N (%) |
|
Age |
<30 |
52 (26%) |
|
30-40 |
113 (56.5%) |
|
|
>40 |
35 (17.5%) |
|
|
Physical Activity |
Low |
145 (72.5%) |
|
Moderate |
52 (26.0%) |
|
|
High |
3 (1.5%) |
|
|
Income |
Low |
96 (48.24%) |
|
Moderate |
91 (45.73%) |
|
|
High |
12 (6.03%) |
|
|
Smoking status |
Smoker |
68 (34.0%) |
|
Non-Smoker |
132 (66.0%) |
|
|
Residency |
Urban |
147 (73.5%) |
|
Rural |
53 (26.5%) |
|
|
BMI |
<24.9 |
93 (46.97%) |
|
24.9-30 |
78 (39.39%) |
|
|
>30 |
27 (13.64%) |
|
|
Education |
Elementary |
146 (73.74%) |
|
Academic |
52 (26.26%) |
|
|
Comorbidity |
No |
183 (91.5%) |
|
Diabetes |
8 (4.0%) |
|
|
Hypertension |
1 (0.5%) |
|
|
High Closterolemy |
5 (2.5%) |
|
|
Heart disease |
2 (1.0%) |
|
|
Respiratory Disease |
1 (0.5%) |
|
|
RBC |
Observed |
9 (4.5%) |
|
Non-Observed |
191 (95.5%) |
|
|
WBC |
Observed |
20 (10.0%) |
|
Non-Observed |
180 (90.0%) |
|
|
Round Cell |
Yes |
153 (76.5%) |
|
No |
47 (23.5%) |
Exclusion criteria were as follows:
(1) Azoospermia, absence of sperm in the semen;
(2) Andrological conditions that may affect sperm quality, such as genetic disorders affecting the sex chromosome (e.g., AZFc microdeletion), previous mumps with testicular involvement, severe varicocele (unilateral or bilateral), undescended testicles, previous testicular torsion or scrotal trauma, congenital bilateral absence of the vas deferens (CBAVD), and urogenital infections;
(3) Use of medications known to affect sperm quality, including steroids, finasteride, and calcium channel blockers;
(4) History of cancer;
(5) Known mental disorders;
(6) Substance abuse;
(7) Inability to complete the lifestyle questionnaire.
Semen analysis was performed in all participants as part of the standard procedure. For research purposes, additional sperm testing was conducted on a subset of participants with sufficient remaining sperm samples after standard diagnostic evaluation, including sperm viability assessment, androgen receptor (AR) assay, and sperm DNA fragmentation assessment. The study received approval from the Research Ethics Committee (IR.UMSU.REC.1401.261).
Semen analysis
Semen samples were collected at the hospital by masturbation after a period of sexual abstinence for 3-7 days. The semen analysis was performed manually sensu the World Health Organization guidelines (version V) (WHO 2010). After collection, semen samples were liquefied at 37 °C and then evaluated within a maximum of 1 hour after ejaculation. Semen volume was measured after liquefaction using a wide bore graduated pipette with 0.1 mL divisions. Researchers determined sperm concentration and assessed motility using a phase-contrast microscope (OLYMPUS BX43, Japan) at 200× or 400× magnification. Sperm concentration was measured using standard dilutions as needed, and counting was performed after a 10-15-minute sedimentation period using improved Neubauer hemocytometers. For sperm motility assessment, a wet mount was prepared by placing 10 μL of the semen sample on a 22 mm × 22 mm coverslip. Repeated assessments were performed, with at least 200 spermatozoa examined during each assessment. Sperm morphology was assessed using Tygerberg strict criteria. Slides were stained using the Diff-Quik staining kit (Dade Behring AG, Switzerland). Assessments were performed using a microscope with a 100× oil immersion objective (OLYMPUS BX43, Japan). The analyses were performed by a qualified technician blinded to the study.
Demographic and lifestyle factors studied in relation to sperm quality
Demographic and lifestyle data were collected using a self-administered questionnaire before or after the semen collection procedure. The questionnaire covered potential risk factors. Participants were given explanations of the questionnaire items before completing it. In this study, participants were categorized based on certain characteristics. The categorization is presented in Table 1, which describes the grouping of variables such as age, physical activity, income, smoking status, place of residence, BMI, and other relevant factors. Regarding physical activity, participants were divided into three groups: low, moderate, and high. However, due to the small number of participants in the high physical activity group (only three individuals), the analysis was limited to two groups: low physical activity and moderate/high physical activity. Similarly, for the BMI variable, individuals with a BMI less than 18.5 (only two participants) were considered to be of normal weight.
Statistical processing of collected data
Continuous variables are presented as mean and standard deviation; qualitative variables are presented as frequency (%). The Kolmogorov-Smirnov test, Q-Q plot, and histogram were used to check for normality of distribution. In case of non-compliance with the assumption of normal distribution, bootstrapping was employed. If no statistically significant differences were observed between the results, tests assuming a normal distribution were subsequently applied. Multiple regression analysis was used to examine the relationship between sperm motility, sperm count (in millions), sperm morphology, and sperm concentration (in millions). The results are presented as a coefficient (β) and the corresponding 95% confidence interval (CI). The model was built using a backward stepwise selection algorithm. All variables with a p-value of less than 0.1 in the univariate analysis were considered as potential candidates for inclusion in the multivariate linear regression model.
Results
The mean and 95% confidence interval for sperm count (in millions), concentration (in millions), morphology, and motility were 114.61 (104.28-125.184), 37.76 (35.13-40.36), 0.057 (0.052-0.062), and 0.47 (0.45-0.49), respectively. Table 2 shows that with every 10-year increase in age, sperm motility decreases by 5.39%. Furthermore, moderate or high physical activity, compared to low activity, was significantly associated with higher sperm motility (β=10.33; 95% CI: 6.73-13.91). Individuals with moderate or high income had significantly higher sperm motility vs. those with low income (β=3.74; 95% CI: 0.58-6.89). The adjusted R-squared value of 0.343 implies that the model explains approximately 34.3% of the variation in sperm motility. Table 3 examines the relationship between various variables and sperm count. With each year of increasing age, sperm count decreases by 3.41 million. Men with high physical activity had a higher sperm count.
Table 2. Crude and adjusted coefficients and 95% confidence intervals (CI) for association between studied variables and sperm motility
|
Variables |
Crude Coeff (95% CI) |
P-value |
Adjusted Coeff (95% CI) |
P-value |
|
|
age (per 10 years) |
-7.83 (-10.81, -4.85) |
<0.001 |
-5.39 (-7.93, -2.64) |
<0.001 |
|
|
Physical Activity |
|
|
|||
|
Low |
1 |
|
1 |
|
|
|
Moderate or high |
14.44 (10.85, 18.03) |
<0.001 |
10.33 (6.73-13.91) |
<0.001 |
|
|
Income |
|
|
|||
|
Low |
1 |
|
1 |
|
|
|
Moderate or High |
7.12 (3.6-10.65) |
<0.001 |
3.74 (0.58-6.89) |
0.02 |
|
|
Smoking status |
|
|
|||
|
Smoker |
|
1 |
|
||
|
Non-Smoker |
8.29 (4.58-11.99) |
0.002 |
5.01 (1.67-8.33) |
0.003 |
|
|
Residency |
|
|
|||
|
Urban |
1 |
|
1 |
|
|
|
Rural |
3.76 (1.38-8.46) |
0.037 |
2.41 (-1.01-5.81) |
0.17 |
|
|
Adjusted R2 |
|
0.343 |
|
||
Table 3. Crude and adjusted coefficients and 95% confidence intervals (CI) for association between studied variables and sperm count (Million)
|
Variables |
Crude Coeff (95% CI) |
P-value |
Adjusted Coeff (95% CI) |
P-value |
|
|
age (per 10 years) |
-43.45 (-60.72 - -26.20) |
<0.001 |
-34.11 (-50.02 - -18.21) |
<0.001 |
|
|
Physical Activity |
|
|
|||
|
Low |
1 |
|
1 |
|
|
|
Moderate or high |
68.01 (46.24-89.76) |
<0.001 |
42.33 (20.55-64.11) |
<0.001 |
|
|
Income |
|
|
|||
|
Low |
1 |
|
1 |
|
|
|
Moderate or High |
7.12 (3.6-10.65) |
<0.001 |
39.05 (19.88-58.21) |
0.02 |
|
|
Smoking status |
|
|
|||
|
Smoker |
1 |
|
1 |
|
|
|
Non-Smoker |
40.42 (18.76-62.08) |
<0.001 |
19.63 (-0.34-39.59) |
0.003 |
|
|
BMI |
-3.14 (-4.93 - -1.36) |
<0.001 |
-1.71 (-3.32 - -0.11) |
0.036 |
|
|
Adjusted R2 |
|
0.373 |
|
||
In addition, individuals with moderate or high income and non-smokers had a higher sperm count. A higher BMI was also associated with a lower sperm count. Overall, Table 4 suggests that younger age, moderate or high physical activity, higher income, and smoking cessation are associated with better sperm morphology in the studied population. Table 5 shows that younger age, moderate or high physical activity, and smoking cessation are associated with higher sperm concentration in the studied population. The study showed that increasing age is associated with a decrease in sperm motility, count, morphology, and concentration. Moderate or high physical activity and smoking cessation are associated with improvements in all sperm parameters. Higher income is associated with improved sperm motility, count, and morphology. Increased BMI is associated with a decrease in sperm count, but no statistically significant association was observed with other sperm parameters. Our results show that place of residence (urban or rural area) does not significantly affect sperm parameters. However, minor effects were observed (e.g., a decrease in sperm motility in urban residents), which were not, however, statistically significant.
Table 4. Crude and adjusted coefficients and 95% confidence intervals (CI) for association between studied variables and sperm morphology
|
Variables |
Crude Coeff (95% CI) |
P-value |
Adjusted Coeff (95% CI) |
P-value |
|
|
age (per 10 years) |
-1.45 (-2.29 - -0.61) |
<0.001 |
-0.92 (-1.68 - -0.15) |
0.018 |
|
|
Physical Activity |
|
|
|||
|
Low |
1 |
|
1 |
|
|
|
Moderate or high |
3.51 (2.51-4.52) |
<0.001 |
2.63 (1.59-3.69) |
<0.001 |
|
|
Income |
|
|
|||
|
Low |
1 |
|
1 |
|
|
|
Moderate or High |
1.75 (0.78-2.72) |
<0.001 |
1.03 (0.12-1.96) |
0.027 |
|
|
Smoking status |
|
|
|||
|
Smoker |
1 |
|
1 |
|
|
|
Non-Smoker |
1.81 (0.78-2.84) |
<0.001 |
1.03 (0.06-1.99) |
0.035 |
|
|
Adjusted R2 |
|
0.249 |
|
||
Table 5. Crude and adjusted coefficients and 95% confidence intervals (CI) for association between studied variables and sperm concentration (Milion)
|
Variables |
Crude Coeff (95% CI) |
P-value |
Adjusted Coeff (95% CI) |
P-value |
|
|
age (per 10 years) |
-8.92 (-13.26 - -4.57) |
<0.001 |
-6.04 (-10.18 - -1.91) |
<0.001 |
|
|
Physical Activity |
|
|
|||
|
Low |
1 |
|
1 |
|
|
|
Moderate or high |
13.86 (8.33-19.41) |
<0.001 |
8.49 (2.92-14.06) |
0.003 |
|
|
Smoking status |
|
|
|||
|
Smoker |
1 |
|
1 |
|
|
|
Non-Smoker |
10.67 (5.34-15.99) |
<0.001 |
7.64 (2.56-27.23) |
0.022 |
|
|
Adjusted R2 |
|
0.284 |
|
||
Discussion
This study aimed to investigate the influence of demographic, clinical, and lifestyle factors on conventional sperm parameters in men undergoing infertility evaluation. We obtained some interesting results. Our findings indicated an inverse correlation between age and sperm parameters, which supported the data by Verón et al. regarding the influence of age on sperm parameters [42]. Our results are similar to those of Stone et al., who discovered adverse associations between age and ejaculate volume, sperm concentration, and progressive motility [23]. Oliveira et al. found an association between age and ejaculate volume, as well as progressive sperm motility [43]. They also revealed a correlation between age and sperm count, which was consistent with the findings of Harris et al. regarding the importance of sperm concentration and noted a decrease in spermatid concentration in the seminiferous tubules with age, leading to a decrease in sperm concentration [44].
Based on our results, sperm count appears to be the parameter most strongly dependent on age. Thus, the decline in endocrine function that occurs with age may explain the observed age-related deterioration [44-45]. Harris et al. found that the most significant changes in sperm quality are oligospermia, asthenozoospermia, and teratospermia. These changes indicate a gradual deterioration of the typical sperm morphology, similar to a decrease of 0.2-0.9% for each year of life [44]. Previous studies have shown that over 20 years, 4-18% of sperm exhibit abnormal morphology [46]. One of the key findings of this study is the significant decrease in sperm parameters with increasing age. This observation is consistent with previous studies indicating that increasing age is associated with a decrease in sperm concentration, motility, and morphology. For example, a study by Jimbo showed that male fertility declines with age due to a combination of factors such as hormonal changes, increased sperm DNA fragmentation, and decreased overall testicular function [47].
These changes may be based on biological mechanisms such as oxidative stress and a decrease in cellular repair mechanisms over time [47]. The results of our study showed that a high body mass index (BMI) significantly reduces the number of sperm, but we observed no statistically significant correlation with other sperm parameters. A recent study examining variables associated with semen quality in couples seeking assistance at a reproductive clinic showed that men with poor semen quality were three times more likely to be obese, compared with men with satisfactory semen quality. In addition, a striking inverse relationship was observed between sperm quality indicators and BMI in men with normal semen quality [48-49]. This study revealed an inverse correlation between overweight/obesity and the total number, normal morphology, and motility of sperm cells in each individual. At a BMI greater than 30 kg/m2, the concentration, morphology, and number of normally motile spermatozoa in the ejaculate decreased.
Several studies have reported an inverse correlation between sperm concentration/total sperm count and obesity assessed by body mass index (BMI) [26]. Our results support the findings of previous studies [26-30] that demonstrated an inverse correlation between body weight and total sperm count. A previous meta-analysis revealed a J-shaped relationship between BMI categories and the likelihood of oligospermia or azoospermia [27]. However, two recent multicenter studies with large sample sizes exhibited no association between BMI and sperm quality [50-53]. The etiology of the relationship between obesity and sperm production is complex and unclear. It has been shown that overweight and obesity (especially central obesity) affect GnRH-FSH/LH pulsation, which can disrupt the functions of Leydig and Sertoli cells and thus hinder the release of sex hormones and the production of mature sperm [62-63].
According to our study, smokers showed a significant decrease in sperm parameters, compared with non-smokers. Studies on the effect of tobacco consumption on sperm parameters have shown that semen volume, total motility, percentage of morphologically normal spermatozoa, sperm viability, and sperm membrane integrity are significantly reduced in smokers vs. non-smokers [54-55]. Our study also confirmed these findings. Regarding cigarette smoking, our results are consistent with a meta-analysis that showed the harmful effects of smoking on sperm motility [52]. Jong et al. demonstrated that cigarette smoking does not appear to significantly affect sperm parameters such as volume, sperm count, motility, and morphology in the studied population [56].
In contrast to this study, the results of our study demonstrated that smoking reduces all sperm parameters. Cigarette smoking is a modifiable lifestyle aspect that affects sperm quality, but there are discrepancies regarding the specific amount and duration of time required for this effect. Mostafa et al. identified a direct relationship between the amount and duration of smoking and its effect on sperm characteristics. They observed that people who smoked heavily for a long period of time had poorer sperm function [53].
The results of our study show that men engaging in moderate or intense physical activity had higher mean values of sperm parameters (motility, morphology, count, concentration) vs. men with low levels of physical activity. Furthermore, a statistically significant difference in sperm cell morphology was observed between the two groups. Men who regularly engage in physical activity demonstrate better sperm quality vs. men leading a sedentary lifestyle [57]. Moreover, physical activity can potentially improve both sperm count and motility [58]. Indeed, physical exercise, by increasing testicular antioxidant protection, reducing levels of pro-inflammatory cytokines, and enhancing the process of steroidogenesis, leads to improved spermatogenesis and sperm quality in cases of lifestyle-induced infertility [60].
Semen quality is influenced by various factors, including geographical differences. Our study revealed a correlation between place of residence, particularly urban living, and below-average semen characteristics. This finding is consistent with the results of a previous study by Zhou et al. [59]. However, our study did not find a statistically significant difference in the mean values of sperm parameters. The study showed a significant correlation between the household income level of the participants and abnormal semen parameters. There are few studies investigating the relationship between sperm characteristics and household income. Nevertheless, Janewich et al. documented that men with lower incomes had increased levels of perceived stress, which affected their sperm characteristics [61]. The discrepancy between this study and our findings may be explained by the participants’ adherence to a healthy lifestyle and stable income, even in the lowest income group in this study.
The results of our study demonstrated a decrease in sperm parameters in men with pre-existing medical conditions, but statistical significance was not confirmed. Our study expands our understanding of male infertility and its correlation with potential risk factors; however, it has some limitations. Given the nature of the study, we were only able to identify correlations between several factors and semen parameters, but we could not establish a definitive causal relationship. Our results may not be applicable to the general population, as all participants were specifically selected from an andrology clinic, and the study was conducted in a single center. No measurements of hormonal analysis or functional factors such as DNA fragmentation index and sperm oxidative stress were performed. Incorporating such characteristics could improve our understanding of the underlying mechanism.
Conclusion
This study represents a significant step forward in understanding male fertility, examining the combined influence of various factors. By considering age, sociodemographic characteristics, lifestyle, and medical history in combination, we obtained a more accurate and useful picture of male fertility, reflecting the complexities of real-life situations. The results necessitate a paradigm shift from an exclusive focus on individual parameters to a comprehensive consideration of the individual in the context of determining fertility. This enhanced understanding will allow for more precise diagnostic and treatment protocols for male infertility. Further research is needed to delve deeper into these interrelationships, enabling the application of personalized strategies and treatment methods.
Conflict of interest
The authors declare that they have no competing financial interests or personal relationships that could have influenced the study reported in this paper.
Acknowledgements
We thank all participants for taking the time to complete the questionnaires.
Author contributions
Farzad Maleki analyzed the data. Hojat Ghasemnejad-Berengi and Hamidreza Farrokh-Eslamlou wrote the manuscript. Sonia Sadeghpour and Tahereh Behroozi-Lak contributed to the development of the research concept and also prepared and edited the manuscript. Robabeh Bahadori and Farzad Maleki confirm the authenticity of all original data. All authors have read and approved the final version of the manuscript.
Ethical approval and consent to participate
This study was approved by the Ethics Committee of the Urmia University of Medical Sciences under number IR.UMSU.REC.1401.261. We, the authors of this article, also confirm that we did not use artificial intelligence (AI) or AI technologies in the preparation of this manuscript.
- Mascarenhas MN, Flaxman SR, Boerma T, Vanderpoel S, Stevens GA. National, regional, and global trends in infertility prevalence since 1990: A systematic analysis of 277 health surveys. PLoS Medicine 2012; 9(12): e1001356. https://doi.org/10.1371/journal.pmed.1001356.
- Shah KM, Gamit KG, Raval MA, Vyas NY. Male infertility: A scoping review of prevalence, causes and treatments. Asian Pacific Journal of Reproduction 2021; 10(5): 195-202. https://doi.org/10.4103/2305-0500.326717.
- World Health Organization. WHO Laboratory Manual for the Examination of Human Semen and Sperm-Cervical Mucus Interaction. 4th Ed. Cambridge: Cambridge University Press. 1999. 136 p.
- Brugh VM 3rd, Lipshultz LI. Male factor infertility: evaluation and management. Med Clin North Am 2004; 88(2): 367-385. https://doi.org/10.1016/S0025-7125(03)00150-0.
- Hirsh A. Male subfertility. BMJ 2003; 327(7416): 669-672. https://doi.org/10.1136/bmj.327.7416.669.
- Lotti F, Maggi M. Ultrasound of the male genital tract in relation to male reproductive health. Hum Reprod Update 2015; 21(1): 56-83. https://doi.org/10.1093/humupd/dmu042.
- Cooper TG, Noonan E, Von Eckardstein S, Auger J, Baker HG, Behre HM, et al. World Health Organization reference values for human semen characteristics. Hum Reprod Update 2010; 16(3): 231-245. https://doi.org/10.1093/humupd/dmp048.
- Rolland M, Le Moal J, Wagner V, Royère D, De Mouzon J. Decline in semen concentration and morphology in a sample of 26 609 men close to general population between 1989 and 2005 in France. Hum Reprod 2013; 28(2): 462-470. https://doi.org/10.1093/humrep/des415.
- Moein MR, Shojaeefar E, Taghizabet N, Jazayeri M, Fashami MA, Aliakbari F, et al. Prevalence of primary infertility in Iranian men; A systematic review. Archives of Men's Health 2021; 5(1): e12. https://doi.org/10.22037/mhj.v5i1.34339.
- Khatun A, Rahman MS, Pang MG. Clinical assessment of male fertility. Obstet Gynecol Sci 2018; 61(2): 179-191. https://doi.org/10.5468/ogs.2018.61.2.179
- Zeqiraj A, Beadini S, Beadini N, Aliu H, Gashi Z, Elezaj S, et al. Male infertility and sperm DNA fragmentation. Open Access Maced J Med Sci 2018; 6(8): 1342-1345. https://doi.org/10.3889/oamjms.2018.311.
- Agarwal A, Baskaran S, Parekh N, Cho CL, Henkel R, Vij S, et al. Male infertility. Lancet 2021; 397(10271): 319-333. https://doi.org/10.1016/s0140-6736(20)32667-2.
- Gaskins AJ, Mendiola J, Afeiche M, Jørgensen N, Swan SH, Chavarro JE. Physical activity and television watching in relation to semen quality in young men. Br J Sports Med 2015; 49(4): 265-270. https://doi.org/10.1136/bjsports-2012-091644.
- Mikkelsen EM, Riis AH, Wise LA, Hatch EE, Rothman KJ, Cueto HT, et al. Alcohol Consumption and Fecundability: Prospective Danish Cohort Study. BMJ 2016; 354: i4262. https://doi.org/10.1136/bmj.i4262.
- Shi X, Chan CP, Waters T, Chi L, Chan DY, Li TC. Lifestyle and demographic factors associated with human semen quality and sperm function. Syst Biol Reprod Med 2018; 64(5): 358-367. https://doi.org/10.1080/19396368.2018.1491074.
- Sharma A. Male infertility, evidences, risk factors, causes, diagnosis and management in human. iMed Pub J 2017; 5(3): 188. https://doi.org/10.21767/2386-5180.1000188.
- Kasman AM, Del Giudice F, Eisenberg M. New insights to guide patient care: The bidirectional relationship between male infertility and male health. Fertil Steril 2020; 113(3): 469-477. https://doi.org/10.1016/j.fertnstert.2020.01.002.
- Klonoff-Cohen HS, Natarajan L. The effect of advancing paternal age on pregnancy and live birth rates in couples undergoing in vitro fertilization or gamete intrafallopian transfer. Am J Obstet Gynecol 2004; 191(2): 507-514. https://doi.org/10.1016/j.ajog.2004.01.035.
- Frattarelli JL, Miller KA, Miller BT, Elkind-Hirsch K, Scott Jr RT. Male age negatively impacts embryo development and reproductive outcome in donor oocyte assisted reproductive technology cycles. Fertil Steril 2008; 90(1): 97-103. https://doi.org/10.1016/j.fertnstert.2007.06.009.
- Sartorius GA, Nieschlag E. Paternal age and reproduction. Hum Reprod Update 2010; 16(1): 65-79. https://doi.org/10.1093/humupd/dmp027.
- Winkle T, Rosenbusch B, Gagsteiger F, Paiss T, Zoller N. The correlation between male age, sperm quality and sperm DNA fragmentation in 320 men attending a fertility center. J Assist Reprod Genet 2009; 26(1): 41-46. https://doi.org/10.1007/s10815-008-9277-3.
- Kidd SA, Eskenazi B, Wyrobek AJ. Effects of male age on semen quality and fertility: A review of the literature. Fertil Steril 2001; 75(2): 237-248. https://doi.org/10.1016/s0015-0282(00)01679-4.
- Stone BA, Alex A, Werlin LB, Marrs RP. Age thresholds for changes in semen parameters in men. Fertil Steril 2013; 100(4): 952-958. https://doi.org/10.1016/j.fertnstert.2013.05.046.
- Johnson SL, Dunleavy J, Gemmell NJ, Nakagawa S. Consistent age dependent declines in human semen quality: A systematic review and meta-analysis. Ageing Res Rev 2015; 19: 22-33. https://doi.org/10.1016/j.arr.2014.10.007.
- Rosen H. Is obesity a disease or a behavior abnormality? Did the AMA get it right? Mo Med 2014; 111(2): 104-108. https://pubmed.ncbi.nlm.nih.gov/30323513.
- Jensen TK, Andersson AM, Jørgensen N, Andersen AG, Carlsen E, Petersen JH, et al. Body mass index in relation to semen quality and reproductive hormones among 1,558 Danish men. Fertil Steril 2004; 82(4): 863-870. https://doi.org/10.1016/j.fertnstert.2004.03.056.
- Sermondade N, Faure C, Fezeu L, Shayeb AG, Bonde JP, Jensen TK, et al. BMI in relation to sperm count: An updated systematic review and collaborative meta-analysis. Hum Reprod Update 2013; 19(3): 221-231. https://doi.org/10.1093/humupd/dms050.
- Aggerholm AS, Thulstrup AM, Toft G, Ramlau-Hansen CH, Bonde JP. Is overweight a risk factor for reduced semen quality and altered serum sex hormone profile? Fertil Steril 2008; 90(3): 619-626. https://doi.org/10.1016/j.fertnstert.2007.07.1292.
- MacDonald AA, Herbison GP, Showell M, Farquhar CM. The impact of body mass index on semen parameters and reproductive hormones in human males: A systematic review with meta-analysis. Hum Reprod Update 2010; 16(3): 293-311. https://doi.org/10.1093/humupd/dmp047.
- Håkonsen LB, Thulstrup AM, Aggerholm AS, Olsen J, Bonde JP, Andersen CY, et al. Does weight loss improve semen quality and reproductive hormones? Results from a cohort of severely obese men. Reprod Health 2011; 8: 24. https://doi.org/10.1186/1742-4755-8-24.
- Lazaros L, Hatzi E, Markoula S, Takenaka A, Sofikitis N, Zikopoulos K, et al. Dramatic reduction in sperm parameters following bariatric surgery: Report of two cases. Andrologia 2012; 44(6): 428-432. https://doi.org/10.1111/j.1439-0272.2012.01300.x.
- World Health Organization. Global Status Report on Alcohol and Health. 2014 edition. Geneva: WHO. 2014; 376 p. https://www.who.int/publications/i/item/global-status-report-on-alcohol-and-health-2014.
- Condorelli RA, Calogero AE, Vicari E, La Vignera S. Chronic consumption of alcohol and sperm parameters: our experience and the main evidences. Andrologia 2015; 47(4): 368-379. https://doi.org/10.1111/and.12284.
- Anifandis G, Bounartzi T, Messini CI, Dafopoulos K, Sotiriou S, Messinis IE. The impact of cigarette smoking and alcohol consumption on sperm parameters and sperm DNA fragmentation (SDF) measured by Halosperm(®). Arch Gynecol Obstet 2014; 290(4): 777-782. https://doi.org/10.1007/s00404-014-3281-x.
- Hamad MF, Shelko N, Kartarius S, Montenarh M, Hammadeh ME. Impact of cigarette smoking on histone (H2B) to protamine ratio in human spermatozoa and its relation to sperm parameters. Andrology 2014; 2(5): 666-677. https://doi.org/10.1111/j.2047-2927.2014.00245.x.
- Keskin MZ, Budak S, Gubari S, Durmaz K, Yoldas M, Celik O, et al. Do cigarette and alcohol affect semen analysis? Arch Ital Urol Androl 2016; 88(1): 56-59. https://doi.org/10.4081/aiua.2016.1.56.
- Farhud DD. Impact of Lifestyle on Health. Iran J Public Health 2015; 44(11): 1442-1444. https://pubmed.ncbi.nlm.nih.gov/26744700.
- Martins AD, Majzoub A, Agawal A. Metabolic syndrome and male fertility. World J Mens Health 2019; 37(2): 113-127. https://doi.org/10.5534/wjmh.180055.
- Muhamad S, Sengupta P, Ramli R, Nasir A. Sociodemographic factors associated with semen quality among Malaysian men attending fertility clinic. Andrologia 2019; 51(10): e13383. https://doi.org/10.1111/and.13383.
- Guo D, Li S, Behr B, Eisenberg ML. Hypertension and Male Fertility. World J Mens Health 2017; 35(2): 59-64. https://doi.org/10.5534/wjmh.2017.35.2.59.
- Huang R, Chen J, Guo B, Jiang C, Sun W. Diabetes-induced male infertility: Potential mechanisms and treatment options. Mol Med 2024; 30(1): 11. https://doi.org/10.1186/s10020-023-00771-x.
- Verón GL, Tissera AD, Bello R, Beltramone F, Estofan G, Molina RI, et al. Impact of age, clinical conditions, and lifestyle on routine semen parameters and sperm kinematics. Fertil Steril 2018; 110(1): 68-75.e4. https://doi.org/10.1016/j.fertnstert.2018.03.016.
- Oliveira JB, Petersen CG, Mauri AL, Vagnini LD, Baruffi RL, Franco Jr JG. The effects of age on sperm quality: An evaluation of 1,500 semen samples. JBRA Assist Reprod 2014; 18(2): 34-41. https://doi.org/10.5935/1518-0557.20140002.
- Harris ID, Fronczak C, Roth L, Meacham RB. Fertility and the aging male. Rev Urol 2011; 13(4): e184-e190. https://pubmed.ncbi.nlm.nih.gov/22232567.
- Neaves WB, Johnson L, Porter JC, Parker Jr CR, Petty CS. Leydig cell numbers, daily sperm production, and serum gonadotropin levels in aging men. J Clin Endocrinol Metab 1984; 59(4): 756-763. https://doi.org/10.1210/jcem-59-4-756.
- Auger J, Kunstmann JM, Czyglik F, Jouannet P. Decline in semen quality among fertile men in Paris during the past 20 years. N Engl J Med 1995; 332(5): 281-285. https://doi.org/10.1056/nejm199502023320501.
- Jimbo M, Kunisaki J, Ghaed M, Yu V, Flores HA, Hotaling JM. Fertility in the aging male: A systematic review. Fertil Steril 2022; 118(6): 1022-1034. https://doi.org/10.1016/j.fertnstert.2022.10.035.
- Magnusdottir EV, Thorsteinsson T, Thorsteinsdottir S, Heimisdottir M, Olafsdottir K. Persistent organochlorines, sedentary occupation, obesity and human male subfertility. Hum Reprod 2005; 20(1): 208-215. https://doi.org/10.1093/humrep/deh569.
- Hammoud AO, Gibson M, Peterson CM, Hamilton BD, Carrell DT. Obesity and male reproductive potential. J Androl 2006; 27(5): 619-626. https://doi.org/10.2164/jandrol.106.000125.
- Cherry N, Povey AC, McNamee R, Moore H, Baillie H, Clyma JA, et al. Occupation exposures and sperm morphology: A case-referent analysis of a multi-centre study. Occup Environ Med 2014; 71(9): 598-604. https://doi.org/10.1136/oemed-2013-101996.
- Eisenberg ML, Kim S, Chen Z, Sundaram R, Schisterman EF, Buck Louis GM. The relationship between male BMI and waist circumference on semen quality: Data from the LIFE study. Hum Reprod 2014; 29(2): 193-200. https://doi.org/10.1093/humrep/det428.
- Sharma R, Harlev A, Agarwal A, Esteves SC. Cigarette smoking and semen quality: A new meta-analysis examining the effect of the 2010 World Health Organization laboratory methods for the examination of human semen. Eur Urol 2016; 70(4): 635-645. https://doi.org/10.1016/j.eururo.2016.04.010.
- Mostafa RM, Nasrallah YS, Hassan MM, Farrag AF, Majzoub A, Agarwal A. The effect of cigarette smoking on human seminal parameters, sperm chromatin structure and condensation. Andrologia 2018; 50(3): e12910. https://doi.org/10.1111/and.12910.
- Amor H, Hammadeh ME, Mohd I, Jankowski PM. Impact of heavy alcohol consumption and cigarette smoking on sperm DNA integrity. Andrologia 2022; 54(7): e14434. https://doi.org/10.1111/and.14434.
- Henriques MC, Santiago J, Patrício A, Herdeiro MT, Loureiro S, Fardilha M. Smoking induces a decline in semen quality and the activation of stress response pathways in sperm. Antioxidants (Basel) 2023; 12(10): 1828. https://doi.org/10.3390/antiox12101828.
- De Jong AM, Menkveld R, Lens JW, Nienhuis SE, Rhemrev JP. Effect of alcohol intake and cigarette smoking on sperm parameters and pregnancy. Andrologia 2014; 46(2): 112-117. https://doi.org/10.1111/and.12054.
- Lalinde-Acevedo PC, Mayorga-Torres BJ, Agarwal A, Du Plessis SS, Ahmad G, Cadavid ÁP, et al. Physically active men show better semen parameters than their sedentary counterparts. Int J Fertil Steril 2017; 11(3): 156-165. https://doi.org/10.22074/ijfs.2017.4881.
- Nematollahi A, Kazeminasab F, Tavalaee M, Marandi SM, Ghaedi K, Nazem MN, et al. Effect of aerobic exercise, low‐fat and high‐fat diet on the testis tissue and sperm parameters in obese and nonobese mice model. Andrologia 2019; 51(6): e13273. https://doi.org/10.1111/and.13273.
- Zhou N, Cui Z, Yang S, Han X, Chen G, Zhou Z, et al. Air pollution and decreased semen quality: A comparative study of Chongqing urban and rural areas. Environ Pollut 2014; 187: 145-152. https://doi.org/10.1016/j.envpol.2013.12.030.
- Minas A, Fernandes ACC, Maciel Junior VL, Adami L, Intasqui P, Bertolla RP. Influence of physical activity on male fertility. Andrologia 2022; 54(7): e14433. https://doi.org/10.1111/and.14433.
- Janevic T, Kahn LG, Landsbergis P, Cirillo PM, Cohn BA, Liu X, et al. Effects of work and life stress on semen quality. Fertil Steril 2014; 102(2): 530-538. https://doi.org/10.1016/j.fertnstert.2014.04.021.
- Hammoud AO, Gibson M, Peterson CM, Meikle AW, Carrell DT. Impact of male obesity on infertility: a critical review of the current literature. Fertil Steril 2008; 90(4): 897-904. https://doi.org/10.1016/j.fertnstert.2008.08.026.
- Hammoud AO, Wilde N, Gibson M, Parks A, Carrell DT, Meikle AW. Male obesity and alteration in sperm parameters. Fertil Steril 2008; 90(6): 2222-2225. https://doi.org/10.1016/j.fertnstert.2007.10.011.
Received 8 December 2024, Revised 9 April 2025, Accepted 5 June 2025
© 2024, Russian Open Medical Journal
Correspondence to Hojat Ghasemnejad‐Berenji. E-mail: h_ghasem_nejad@yahoo.com.
