A metabolomic perspective on the mechanisms by which environmental pollutants and lifestyle lead to male infertility

The incidence of male infertility (MI) is rising annually. According to epidemiological studies, environmental pollution (e.g., organic, inorganic, and air pollutants), occupational exposure (e.g., high temperature, organic solvents, and pesticides), and poor lifestyle (e.g., diet, sleep, smoking, alcohol consumption, and exercise) are important non-genetic causative factors of MI. Due to multiple and complex causative factors, the dose-effect relationship, and the uncertainty of pathogenicity, the pathogenesis of MI is far from fully clarified. Recent data show that the pathogenesis of MI can be monitored by the metabolites in serum, seminal plasma, urine, testicular tissue, sperm, and other biological samples. It is considered that these metabolites are closely related to MI phenotypes and can directly reflect the individual pathological and physiological conditions. Therefore, qualitative and quantitative analysis of the metabolome, the related metabolic pathways, and the identification of biomarkers will help to explore the MI-related metabolic problems and provide valuable insights into its pathogenic mechanisms. Here, we summarized new findings in MI metabolomics biomarkers research and their abnormal metabolic pathways triggered by the presented non-genetic risk factors, providing a metabolic landscape of semen and seminal plasma in general MI patients. Then, we compared the similarities and differences in semen and seminal plasma biomarkers between MI patients exposed to environmental and poor lifestyle factors and MI patients in general, and summarized some common biomarkers. We provide a better understanding of the biological underpinnings of MI pathogenesis, which might offer novel diagnostic, prognostic, and precise treatment approaches to MI.

Frequency, morbidity and equity - the case for increased research on male fertility

Currently, most men with infertility cannot be given an aetiology, which reflects a lack of knowledge around gamete production and how it is affected by genetics and the environment. A failure to recognize the burden of male infertility and its potential as a biomarker for systemic illness exists. The absence of such knowledge results in patients generally being treated as a uniform group, for whom the strategy is to bypass the causality using medically assisted reproduction (MAR) techniques. In doing so, opportunities to prevent co-morbidity are missed and the burden of MAR is shifted to the woman. To advance understanding of men's reproductive health, longitudinal and multi-national centres for data and sample collection are essential. Such programmes must enable an integrated view of the consequences of genetics, epigenetics and environmental factors on fertility and offspring health. Definition and possible amelioration of the consequences of MAR for conceived children are needed. Inherent in this statement is the necessity to promote fertility restoration and/or use the least invasive MAR strategy available. To achieve this aim, protocols must be rigorously tested and the move towards personalized medicine encouraged. Equally, education of the public, governments and clinicians on the frequency and consequences of infertility is needed. Health options, including male contraceptives, must be expanded, and the opportunities encompassed in such investment understood. The pressing questions related to male reproductive health, spanning the spectrum of andrology are identified in the Expert Recommendation.

Associations between urinary biomarkers of exposure to disinfection byproducts and semen parameters: A repeated measures analysis

Toxicological studies have demonstrated that disinfection byproducts (DBPs), particularly haloacetic acids, cause testicular toxicity. However, evidence from human studies is sparse and inconclusive. This study included 1230 reproductive-aged men from the Tongji Reproductive and Environmental (TREE) cohort to investigate the associations between repeated measures of DBP exposures and semen parameters. Urinary dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) as biomarkers of DBP exposures and semen parameters in up to three samples from each man were assessed. The linear mixed effect models were applied to explore the associations between urinary biomarkers of DBP exposures and semen parameters. We found inverse associations of urinary DCAA with sperm count, progressive motility, and total motility (e.g., -14.86%; 95% CI: -19.33%, -10.15% in sperm total motility for the highest vs. lowest quartiles; all P for trends < 0.05). Moreover, urinary TCAA modeled as a continuous variable was negatively associated with sperm progressive motility and total motility, while the inverse associations across increasing urinary TCAA quartiles were seen among leaner men (BMI < 25 kg/m2). Exposure to DBPs reflected by urinary DCAA and TCAA was inversely associated with sperm motility and such effects were more evident among leaner men.

The spermiogram and correlation of seminal fluid parameters in patient attending fertility centre in Lagos, South West Nigeria

BACKGROUND

The determinant of the spermiogram of semen varies in different populations based on several factors ranging, from age to the pathological state of an individual to environmental factors. The aim of the study is to determine the spermiogram of patients that attend fertility clinics in southwest Nigeria and the relationship between the parameters.

METHODOLOGY

This is a cross-sectional study that recruited two hundred and ninety seven (297) patients from two fertility centers in Lagos, Nigeria for the period of January 2021 to November 2022. The sperm samples were collected following WHO standards. The spermiogram was analyzed using an automated sperm analyzer and the descriptive and inference statistics of the study were carried out using R packages (R version 4.2.0).

RESULTS

The result showed the mean age of 43.12±6.95years with median age of 42years. The mean of sperm count and concentration were 114×106 sperm cells and 42×106 per mL with the mean volume of the semen produced by the patients was 2.69mL and average motility (progressive and non-progressive) of the sperm is 47%±19%, 42%±17% has normal morphology. The distributions of the observed variables (seminal fluid parameters) were different from normal distributions in the studied population, such that almost all of them are skewed to the right. The degree of relationship between the sperm parameter were very weak. Nevertheless, specifically, there is a negative correlation between age and sperm count, age and motility, age and volume, and a positive correlation between age and abnormal morphology. The results showed that sperm morphology has a significant effect on motility while sperm morphology significantly depend on sperm count.

CONCLUSION

An increase in sperm volume and concentration improves the sperm morphology and boost the sperm motility, this may increasing the chance of fertility.

The effects of tobacco and cannabis use on semen and endocrine parameters in infertile males

Substances such as tobacco and cannabis can negatively modulate seminal parameters and sex hormones and lead to fertility problems in males. The present study aimed to determine the effect of cigarettes, dipping tobacco, and cannabis on semen parameters and sex hormones in infertile males. A total of 160 infertile healthy participants (cigarette smokers n = 40, dipping tobacco users n = 40, cannabis users n = 40 and infertile controls n = 40) were included in the study. Fasting blood samples were collected from all the participants using the aseptic technique, and semen samples were collected by masturbation following sexual abstinence of 2-7 days. The levels of serum testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were determined using ELISA. The serum level of FSH was significantly higher in cannabis users relative to the control group (p = 0.043). A mild non-significant decrease in sperm count, serum LH and testosterone levels were observed in all drug users compared to controls. In conclusion, chronic use of tobacco and cannabis mildly modulates semen and hormonal parameters in infertile males.

Male Clinical Parameters (Age, Stature, Weight, Body Mass Index, Smoking History, Alcohol Consumption) Bear Minimal Relationship to the Level of Sperm DNA Fragmentation

This retrospective cohort study reports on 1291 males who were the partners of women presenting with infertility requiring assisted reproduction and who had sperm DNA fragmentation (SDF) levels measured by the Halosperm test. These men provided clinical and biometric details which included their age, stature, weight, and body mass index (BMI). Of these men, 562 (43.5%) provided detailed historical records of their smoking and alcohol histories. The aim of this study was to determine whether any clinical and biometric parameters, or main lifestyle factors, had any influence on SDF. We found that the only clinical parameter with a direct correlation was that of advancing age (r = 0.064, p = 0.02), but none of the biometric parameters of stature, weight, or BMI showed any significant correlation. In respect to lifestyle, there were significant correlations with smoking history, but not in the way we expected. Our data showed significantly elevated SDF levels among non-smokers (p = 0.03) compared with smokers. We also found that, among the non-smokers, ex-smokers had higher SDF levels (p = 0.03). With respect to alcohol, consumers did not show any significant differences in SDF levels. These lifestyle findings did not show any significant relevance with respect to an SDF level of <15% or ≥15%. Furthermore, logistic regression analysis excluded age as a confounder in these lifestyle findings. It is therefore concluded that, apart from age, both clinical and lifestyle aspects have minimal relevance to SDF.

Effect of paternal smoking on pre-implantation embryonic development: a prospective cohort study

CONTEXT

Recent studies have failed to demonstrate the negative impact of male tobacco smoking on embryo development, raising the question of its actual implication on natural fecundity and assisted reproductive techniques outcomes.

AIMS

To assess the impact of paternal smoking on embryo development.

METHODS

In this prospective cohort study, 252 men from couples undergoing in vitro fertilisation (IVF) were included. Each patient was interviewed and took a carbon monoxide breath-test, creating three groups: non-smokers (n=113), former smokers (n=81) and active smokers (n=58). The Top-grade embryo ratio (primary endpoint), embryo morphokinetic parameters and clinical outcomes were assessed.

KEY RESULTS

In a multivariate analyses based on 1521 embryos, no significant difference was found in the top-grade embryo ratio between the groups. Tobacco smoking had no impact on clinical outcomes. Compared to non-smokers the time to the pronuclei fading (tPNf, P=0.006) and the time to the first embryonic cleavage (t2, P=0.002) were shorter in smokers, and the t2 was also slightly shorter in former smokers (P=0.045). No other differences were found in the morphokinetic parameters.

CONCLUSION

Even if a few differences were observed in the first timing of embryonic events, this study did not highlight a major embryonic and clinical impact of the paternal smoking status.

IMPLICATION

The results obtained here are reassuring towards IVF outcomes. As maternal smoking is highly controlled in the IVF patients in this study, we speculate that the sperm selection process may limit the adverse effects of tobacco consumption on embryo development.

Impact of heavy alcohol consumption and cigarette smoking on sperm DNA integrity

The purposes of the presents study were to investigate the impact of alcohol consumption and cigarette smoking on semen parameters and sperm DNA quality, as well as to determine whether tobacco smoking, or alcohol consumption causes more deterioration of sperm quality. Two hundred and eleven semen samples of men were included in this study. Four groups were studied: heavy smokers (N = 48), heavy drinkers (N = 52), non-smokers (n = 70), and non-drinkers (n = 41). Semen parameters were determined according to WHO guidelines, protamine deficiency assessed by chromomycin (CMA3) staining, and sperm DNA fragmentation (sDF) evaluated by TUNEL assay. Sperm parameters were significantly higher in non-smokers versus smokers and in non-drinkers versus drinkers (p < 0.005). However, protamine deficiency and sDF were significantly lower in non-smokers versus smokers and in non-drinkers versus drinkers (p < 0.0001). No significant difference in the semen analysis parameters was observed between heavy smokers and heavy drinkers (semen volume: 3.20 ± 1.43 vs. 2.81 ± 1.56 ml, semen count: 65.75 ± 31.32 vs. 53.51 ± 32.67 mill/ml, total motility: 24.27 ± 8.18 vs. 23.75 ± 1.75%, sperm vitality: 36.15 ± 18.57 vs. 34.62 ± 16.65%, functional integrity: 41.56 ± 18.57 vs. 45.96 ± 17.98% and the morphologically normal spermatozoa: 28.77 ± 11.82 vs. 27.06 ± 13.13%, respectively). However, protamine deficiency was significantly higher among drinkers than smokers (37.03 ± 9.75 vs. 33.27 ± 8.56%, p = 0.020). The sDF was also significantly higher among drinkers than smokers (22.37 ± 7.60 vs. 15.55 ± 3.33%, p < 0.0001). Thus, cigarette smoking, and heavy alcohol intake can deteriorate sperm quality. However, alcohol consumption deteriorates sperm maturity and damages DNA integrity at significantly higher rates than cigarette smoking.

Diurnal rhythm of human semen quality: analysis of large-scale human sperm bank data and timing-controlled laboratory study

STUDY QUESTION

Can we identify diurnal oscillations in human semen parameters as well as peak times of semen quality?

SUMMARY ANSWER

Human semen parameters show substantial diurnal oscillation, with most parameters reaching a peak between 1100 and 1500 h.

WHAT IS KNOWN ALREADY

A circadian clock appears to regulate different physiological functions in various organs, but it remains controversial whether diurnal rhythms occur in human semen parameters.

STUDY DESIGN, SIZE, DURATION

The medical record of a provincial human sperm bank (HSB) with 33 430 semen samples collected between 0800 and 1700 h from 1 March 2010 to 8 July 2015 was used to analyze variation in semen parameters among time points. A laboratory study was conducted to collect semen samples (n = 36) from six volunteers at six time points with identical time intervals (2 days plus 4 h) between 6 June and 8 July in 2019, in order to investigate the diurnal oscillation of semen parameters in vivo, with a strictly controlled abstinence period. Therefore, the sperm bank study with a large sample size and the in vivo study with a strictly controlled abstinence period in a 24-h time window could be compared to describe the diurnal rhythms in human semen parameters.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Samples were obtained from potential HSB donors and from participants in the laboratory study who were volunteers, recruited by flyers distributed in the community. Total sperm count, sperm concentration, semen volume, progressive motility and total motility were assessed using computer-aided sperm analysis. In addition, sperm chromatin integrity parameters (DNA fragmentation index and high DNA stainability) were assessed by the sperm chromatin structure assay, and sperm viability was measured with flow cytometry in the laboratory study.

MAIN RESULTS AND THE ROLE OF CHANCE

The 33 430 samples from the HSB showed a temporal variation in total sperm count, sperm concentration, semen volume, progressive motility and total motility (all P < 0.001) between 0800 and 1700 h. Consequently, the eligibility of semen samples for use in ART, based on bank standards, fluctuated with time point. Each hour earlier/later than 1100 h was associated with 1.14-fold risk of ineligibility. Similarly, the 36 samples taken during the 24-h time window showed diurnal oscillation. With the pre-collection abstinence period strictly controlled, most semen parameters reached the most favorable level between 1100 and 1500 h.

LIMITATIONS, REASONS FOR CAUTION

Some of the possible confounding factors, such as energy intake, which might influence semen quality or diurnal rhythms, were not adjusted for in the analyses. In addition, the findings should be considered with caution because the study was conducted in a specific population, time and place, while the timing of oscillations could differ with changing conditions.

WIDER IMPLICATIONS OF THE FINDINGS

The findings could help us to estimate semen quality more precisely and to obtain higher quality sperm for use in ART and in natural conception.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Natural Science Foundation of China (81871208) and National Key R&D Program of China (2017YFC1002001). There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Fipronil and its metabolites in human seminal plasma from Shijiazhuang, north China

Fipronil (FP) is an emerging insecticide which could induce reproductive toxicity in male rats at very low dosage, but the occurrence of FP and its transformation products (FPs) in human seminal plasma and their impacts on human semen quality have not been documented. In this study, FPs including FP, fipronil desulfinyl (FP-DES), fipronil sulfone (FP-SFO), fipronil amide (FP-AM), and fipronil sulfide (FP-SFI), were measured in seminal plasma samples (n = 200), which were collected from Shijiazhuang, north China. The cumulative concentration of FPs (ΣFPs), in the seminal plasma samples ranged from 0.003 to 0.180 ng/mL (median: 0.043 ng/mL). FP-SFO was the major target analyte (median: 0.040 ng/mL), accounting for approximately 42.3-100.0% of the ΣFPs. Significantly higher exposure levels of FPs were found in the overweight or obese group (≥25 kg/m²) vs. the normal BMI group (18.5-25 kg/m²) (ΣFPs: 0.047 vs. 0.033 ng/mL), never smoking group vs. current smoking group (ΣFPs: 0.057 vs. 0.037 ng/mL), and low sexual frequency group (<1 time/week) vs. high sexual frequency group (≥3 times/week) (ΣFPs: 0.048 vs. 0.030 ng/mL). No significant association between FPs and impaired semen quality parameter was found in this study. This is the first time to report FPs' occurrence in human seminal plasma and variations in their concentrations among people with different demographic and behavioral characteristics. Further studies on adverse effects of exposure to FPs on reproductive function are needed.

Environmental and occupational exposures associated with male infertility

The upsurge in male infertility over the last two decades, possibly due to environmental exposure, has raised significant interest, particularly boosted by reports from fertility clinics, which showed that chronic diseases and hereditary or other medical conditions might only partially explain current incidence of male infertility. Both environmental and occupational settings may have a significant role in exposure to complex mixtures of endocrine disruptors (ED), which play a major role in fertility disorders. The aim of this review is to give an insight into the current knowledge on exposure settings which may be associated with male infertility. Our study relied on a systematic search of PubMed, Scopus, and Web of Science for articles published between January 2000 and September 2020. It showed that some well documented factors associated with male infertility include smoking, and physiological disturbances or chronic diseases such as obesity and diabetes, which in turn, may also reflect lifestyle choices and environmental exposures, especially to EDs such as phthalates, bisphenols, pesticides, and flame retardants. However, the number of studies on the aetiology of male infertility is still too low in comparison with the size of affected population. Occupational health follow-ups and medical surveillance do not collect any data on male infertility, even though ED chemicals are part of many technological processes.

Interactive Effects of Unhealthy Lifestyle Behaviors on Testicular Function among Healthy Adult Men: A Cross-Sectional Study in Taiwan

Recently, the role of lifestyle factors in testicular function has developed into a growing area of interest. Based on cross-sectional data on 3283 Taiwanese men, we investigated whether interactive effects of unhealthy lifestyle behaviors were associated with testicular function. The men were recruited from a private screening institute between 2009 and 2015. Lifestyle behaviors (smoking, alcohol drinking, physical activity (PA), sleeping habits, and diet) were obtained by a validated self-reported questionnaire. The men provided a semen sample and had blood drawn for sex hormone measurement. Men who smoked and drank had higher testosterone (T) levels (β = 0.81, p < 0.001) than those who neither smoked nor drank. Men who smoked and had high Western dietary pattern scores had higher T levels-by 0.38 ng/mL (p = 0.03). Those who drank and did not get enough sleep or had high Western dietary pattern scores had elevated T levels-by 0.60 ng/mL (p = 0.005) or 0.45 ng/mL (p = 0.02), respectively. Light PA and insomnia were associated with decreased T levels-by 0.64 ng/mL (p < 0.001). Those who smoked and drank or had light PA or had high Western dietary pattern scores had lower normal sperm morphologies (NSMs)-by 2.08%, 1.77%, and 2.29%, respectively. Moreover, drinkers who had high Western dietary pattern scores had higher sperm concentrations-by 4.63 M/mL (p = 0.04). Awareness and recognition of the long-term impact of lifestyle behaviors and better lifestyle choices may help to optimize the chance of conception amongst couples.

Adverse effects of circadian desynchrony on the male reproductive system: an epidemiological and experimental study

STUDY QUESTION

Is circadian desynchrony a risk factor of male reproductive damage in semen parameters and/or reproductive hormones?

SUMMARY ANSWER

Circadian desynchrony correlates with decrease of sperm count, which was improved when circadian desynchrony was attenuated.

WHAT IS KNOWN ALREADY

Circadian desynchrony caused by work (shift work) and non-work-related reasons is prevalent worldwide and has been found to be associated with decreased female fertility, but whether it harms male reproductive health is unclear.

STUDY DESIGN, SIZE, DURATION

A hybrid research was conducted. (i) A cross-sectional study of 1346 Chinese men in 2007 was used to analyze the association between semen/hormone biomarkers and work-related circadian desynchrony, which was divided into rotating shift work and permanent shift work against non-shift work. (ii) A cohort of 796 Chinese undergraduates from 2013 to 2014 was used to analyzed the association between semen/hormone biomarkers and non-work-related circadian desynchrony (between school days and days off). (iii) The biomarker identified simultaneously in both populations was further validated in male C57BL/6J mice housed under conditions simulating circadian desynchrony.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 17 semen/hormone biomarkers were compared among rotating shift workers and permanent shift workers against non-shift workers in the 1346 reproductive-age Chinese men. A total of 14 semen/hormone biomarker was analyzed in the undergraduate cohort for correlation with non-work-related circadian desynchrony (measured by Munich Chronotype Questionnaire) in 2013 and 2014 and compared between the 2 years. Photoperiod-shifting method was used to establish the mouse model, in which the biomarker was examined and molecular mechanism was explored by apoptosis analysis, DNA content analysis, transcriptome sequencing, real-time PCR and western blotting.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the semen/hormone biomarkers, sperm count was found to be lower in rotating shift workers, who had a higher risk of low sperm count defined by Chinese Ministry of Health (total sperm/ejaculate < 120 × 10⁶) than non-shift workers (odds ratio = 1.26, 95% CI 1.05–1.52). This biomarker was replicated in the undergraduate cohort, where each hour of circadian desynchrony was associated with 1.16 (95% CI 1.02–1.31) fold odds of low sperm count, and sperm count increased during 2014 in men who reduced circadian desynchrony after 2013. A decrease of sperm count with circadian desynchrony and its recovery after removal of circadian desynchrony was also observed in the mouse model. During asynchrony, increased apoptosis was found in seminiferous tubules and the marker genes of post-spermatocyte stage cells were down-regulated. The most enriched functional pathway was homologous recombination, which happened during meiosis.

LIMITATIONS, REASONS FOR CAUTION

The study of human beings was observational while the animal study has potential difference in circadian desynchrony exposure and species susceptibility. Further researches are needed to clarify the causal relationship in men.

WIDER IMPLICATIONS OF THE FINDINGS

These findings provide novel insight to the effect of circadian desynchrony on male reproductive health and a potential strategy for prevention of reproductive damage.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Key R&D Program of China [2017YFC1002001] and National Natural Science Foundation of China [81871208]. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

NA.

Advanced Paternal Age and Sperm DNA Fragmentation: A Systematic Review

Purpose

Male ageing is often associated with defective sperm DNA remodeling mechanisms that result in poorly packaged chromatin and a decreased ability to repair DNA strand breaks. However, the impact of advanced paternal age on DNA fragmentation remains inconclusive. The aim of the present systematic review was to investigate the impact of advancing paternal age (APA) on DNA fragmentation.

Materials and Methods

We conducted a thorough search of listed publications in Scopus, PubMed, and EMBASE, in accordance with the PRISMA guidelines.

Results

We identified 3,120 articles, of which nineteen were selected for qualitative analysis, resulting in a sample of 40,668 men. Of the 19 articles evaluating the impact of APA on DFI% (DNA fragmentation Index) included, 4 were on Normozoospermic and subfertile men, 3 on normozoospermic, Oligoasthenoteratozoospermic and Teratozoospermic, 6 on fertile and infertile men, 4 on just infertile men, and 2 evaluated a general population. Seventeen of the ninrnteen studies demonstrated APA's effect and impact on DFI%.

Conclusions

Although there was no universal definition for APA, the present review suggests that older age is associated with increased DFI. In elderly men with normal semen parameters, further studies should be performed to assess the clinical implications of DFI, as a conventional semen analysis can often fail to detect an etiology for infertility.

Heavy cigarette smoking and alcohol consumption are associated with impaired sperm parameters in primary infertile men

We assessed the concomitant impact of cigarette smoking and alcohol consumption in men presenting for primary couple's infertility. Data from 189 infertile men were analyzed. Semen analysis, serum hormones, and sperm DNA fragmentation (SDF) were obtained. Smoking status was categorized as follows: current nonsmoker (-S), moderate smoker (+MS), and heavy smoker (+HS). Alcohol consumption was categorized as follows: abstainer (-D), moderate drinker (+MD), and heavy drinker (+HD). Descriptive statistics and logistic regression models were applied. Among all the participants, 132 (69.8%), 30 (15.9%), and 27 (14.3%) patients were -S, +MS, and +HS, respectively. In addition, 67 (35.4%), 77 (40.7%) and 45 (23.8%) men were -D, +MD and +HD, respectively. Regarding concomitant habits, 52 (27.5%) patients were nonsmokers and abstainers (-S/-D: Group 1), 91 (48.1%) had at least one recreational habit (-S/+D or +S/-D: Group 2), and 46 (24.3%) were both smokers and drinkers (+S/+D: Group 3). Sperm concentration and progressive motility were lower in +HS and +HD, compared with -S and -D (all P < 0.05), respectively. Similarly, both parameters were significantly lower in Group 3 than Groups 1 and 2 (all P < 0.05). SDF values were higher in Group 3 than Groups 1 and 2 (both P < 0.05). In multivariate analysis, follicle-stimulating hormone (FSH) levels and concomitant +S/+D status were independent predictors of impaired sperm concentration and progressive motility (all P < 0.05). Heavy smoking and heavy drinking were associated with worse seminal parameters than moderate smoking/drinking and nonsmoking/abstaining. When concomitant, +S/+D status has an even greater detrimental effect on semen parameters.

Cigarette smoking is associated with high level of ferroptosis in seminal plasma and affects semen quality

PURPOSE

The effects of cigarette smoking on male semen quality are controversial, and the molecular mechanisms underlying how cigarette smoking affects semen quality are not clear yet.

METHODS

In this study, semen samples from 70 heavy smokers and 75 non-smokers receiving infertility treatment were included. Basic semen parameters in non-smokers and heavy smokers were evaluated. Levels of glutathione (GSH), lipid reactive oxygen species (ROS), iron and GSH-dependent peroxidase 4 (GPX4) protein level were observed in human seminal plasma and in GC-2Spd cells exposed to cigarette smoke condensate (CSC).

RESULTS

Heavy smokers had significantly higher abnormalities (sperm viability and sperm progressive motility) than non-smoking counterparts. Comparing non-smokers group, GSH level was reduced in the group of heavy smokers (P < 0.05). However, the level of lipid ROS and iron were significantly increased (P < 0.05). Besides, GSH level was reduced following treatment with CSC for 24 h, while lipid ROS and iron levels were increased (P < 0.05). However, the levels were reduced after being co-cultured with Ferrostatin-1 (Fer-1) (P < 0.05). The level of GPX4 protein was reduced after being treated with CSC in 24 h, and increased after being co-cultured with Fer-1(P < 0.05).

CONCLUSION

Cigarette smoking is associated with high level of ferroptosis in seminal plasma and affect semen quality.

How does body mass index affect semen parameters and reproductive hormones in infertile males?

OBJECTIVE

The aim of this study was to invastigate the effect of body mass index (BMI) on semen parameters and reproductive hormone levels in infertile males.

MATERIAL AND METHODS

Overall, 858 infertile male patients, aged between 18 and 55 years, referred to our infertility clinic were included in the study. Patients without risk factors, besides obesity, that could affect semen parameters or reproductive hormones were evaluated. Patients were separated into the following three groups: non-obese (<25 kg/m²), overweight (25-29.9 kg/m²), and obese (≥30 kg/m²). Age, semen parameters, and reproductive hormones were evaluated and compared among the groups. In addition, subgroups based on sperm concentration were compared.

RESULTS

Total testosterone and testosterone-estradiol ratio negatively correlated with BMI (p<0.001). A positive correlation was observed between BMI and age (p<0.001). Even when adjusted for age, the decrease in total testosterone was significant in all groups parallel to the increase in BMI. Although age, prolactin level, and total testosterone had a significant relationship in univariate analysis, the only significant parameters were prolactin and total testosterone according to multivariate analysis. There were no significant differences between BMI and semen parameters. No significant difference related to BMI was observed among the infertile groups [severe oligospermia (34.3%), oligospermia (18.2%), and normospermia (47.6%)].

CONCLUSION

A significant negative correlation was observed between increasing BMI and total testosterone. No relationship was observed between BMI and semen parameters except progressive motility. Nevertheless, prospective longitudinal clinical trials with larger sample sizes involving weight loss are needed to understand the precise relationship of BMI with reproductive hormones and semen parameters in the same individual.

Obesity and Reproduction

OBJECTIVE

To provide a comprehensive review and evidence-based recommendations for the delivery of fertility care to women with obesity.

OUTCOMES

The impact of obesity on fertility, fertility treatments, and both short and long-term maternal fetal outcomes was carefully considered.

EVIDENCE

Published literature was reviewed through searches of MEDLINE and CINAHL using appropriate vocabulary and key words. Results included systematic reviews, clinical trials, observational studies, clinical practice guidelines, and expert opinions.

VALUES

The Canadian Fertility & Andrology Society (CFAS) is a multidisciplinary, national non-profit society that serves as the voice of reproductive specialists, scientists, and allied health professionals working in the field of assisted reproduction in Canada. The evidence obtained for this guideline was reviewed and evaluated by the Clinical Practice Guideline (CPG) Committee of the CFAS under the leadership of the principal authors.

BENEFITS, HARMS, AND COSTS

The implementation of these recommendations should assist clinicians and other health care providers in counselling and providing reproductive care to women with obesity.

VALIDATION

This guideline and its recommendations have been reviewed and approved by the membership, the CPG Committee and the Board of Directors of the CFAS.

SPONSORS

Canadian Fertility & Andrology Society.

RECOMMENDATIONS

Twenty-one evidence based recommendations are provided. These recommendations specifically evaluate the impact of obesity on natural fertility, fertility treatments, and maternal-fetal outcomes. Strategies to lose weight and BMI cut-offs are also addressed.

Seminal plasma of men with severe asthenozoospermia contain exosomes that affect spermatozoa motility and capacitation

OBJECTIVE

To characterize in depth and investigate the role of exosomes present in seminal plasma in affecting parameters underlying sperm activity.

DESIGN

In vitro experimental study.

SETTING

Research hospital.

PATIENT(S)

Normozoospermic, severe asthenozoospermic, and post-vasectomy azoospermic men 18-55 years of age were considered for the study. Seminal plasma was collected and processed to separate spermatozoa and exosomes.

INTERVENTION(S)

None.

MAIN OUTCOMES MEASURE(S)

Exosomes from seminal plasma were isolated and characterized by means of nanoparticle tracking analysis, transmission electron microscopy and Western blot. Exosome uptake by spermatozoa was monitored by means of immunofluorescence and flow cytometry. The effect of exosomes on spermatozoa was determined by evaluating progressive motility and capacitation, the latter assessed by means of tyrosine phosphorylation and acrosome reaction.

RESULT(S)

We isolated and characterized exosomes from seminal plasma of normo-, astheno-, and azoospermic patients. They display similar features in terms of shape, size, expression of canonic exosome markers and proteins involved in spermatozoa maturation, and fertilization capacity. After ejaculation, sperm cells are still receptive and are able to take up exosomes in a time- and pH-dependent manner. Exosomes derived from normozoospermic but not from asthenozoospermic individuals improve spermatozoa motility and trigger capacitation. Transfer of cysteine-rich secretory protein 1 from exosomes to spermatozoa may have a role in these phenomena.

CONCLUSION(S)

These findings provide evidence that: 1) sperm can still receive vesicle-derived cargo after ejaculation; 2) sperm motility and ability to undergo capacitation can benefit from exosomal transfer; and 3) semen quality is affected by male tract exosomes.

Decline in semen concentration of healthy Chinese adults: evidence from 9357 participants from 2010 to 2015

The present study aims to analyze sperm concentration trends among young and healthy Chinese adults in Wuhan, Central China, from 2010 to 2015. Semen analysis data from 9357 participants were collected and analyzed using a general linear model and the Cochran–Armitage trend test. A significant decline was observed in sperm concentration (β [standard deviation]: −1.53 [0.16]; P < 0.001). In addition, a decline in sperm density was observed by stratifying student versus nonstudent sperm donors and by analyzing the year of birth or birth year cohort of the participants. Furthermore, the percentage of participants with sperm densities of over 40 × 10⁶ ml⁻¹ significantly decreased with year. Notably, a dramatic decline in sperm density was recorded over the first 5 years of study. This research reported a decline in sperm concentration among young adults in Wuhan, Central China, in 2010–2015.

Diurnal variation in sperm DNA fragmentation: analysis of 11,382 semen samples from two populations and in vivo animal experiments

Circadian rhythms have been found in some reproductive functions phenotypes but remain unclear for sperm DNA fragmentation index (DFI). The present study aims to investigate the diurnal variation of DFI in mice model and men sperm. Adult male mice were sacrificed for sperm DFI with Sperm Chromatin Structure Assay (SCSA) in 24 hours at 6 evenly distributed time points. A cosinor pattern of DFI was observed with a nadir at zeitgeber time 10 AM. In a community population with 630 semen samples collected between 8 AM and 20 PM, the temporal variation of DFI also fit a cosinor pattern with a - 343° acrophase and a nadir at 11 AM (P = .031). In a reproductive-medical-center dataset of 10752 semen samples collected between 7 AM and 11 AM, the decreasing trend of DFI was also confirmed. For the males with multiple samples, intra-individual comparison between different timepoints was performed, and each consecutive hour after 7 AM was also associated with 2.5 (95% CI: -1.0, 5.9)% lower DFI by SCSA or 4.9 (1.9, 7.8)% lower DFI by SCD. Our study reveals a daily diurnal variance in sperm DFI which may suggest a practical approach to get more qualified sperms for natural or assisted reproduction. Abbreviations: BMI, Body mass index; DFI, DNA fragmentation index; MARHCS, Male Reproductive Health in the Chongqing College Students; RMC, Reproductive Medical Center; SCD, Sperm Chromatin Dispersion; SCSA, Sperm Chromatin Structure Assay.

Semen quality and cigarette smoking in a cohort of healthy fertile men

BACKGROUND

Numerous health effects of smoking are well-known; associations with semen quality are uncertain. Most previous studies did not adjust for potential confounders and had limited information on age at smoking initiation or smoking cessation.

METHODS

We investigated 1,631 healthy fertile men in the Nanjing Medical University Longitudinal Investigation of Fertility and the Environment (NMU-LIFE) study. Relationships were examined using multivariable linear regression controlling for potential covariates.

RESULTS

We found a significant decrease in semen volume (β = -0.10, P = 0.001) and total sperm count (β = -0.42, P = 0.037), and significant increase in total motility (β = 6.02, P = 0.037) and progressive motility (β = 5.52, P = 0.037) in ever smokers of pack-years ≥10 compared with never smokers. We observed an inverse dose-dependent relation between smoking pack-years and semen volume (P < 0.001) and total sperm count (P = 0.010) and a positive dose-dependent relation between smoking pack-years and both total motility and progressive motility (P = 0.042 and 0.048, respectively). No significant differences in semen quality were detected among ever smokers with different ages at smoking initiation nor in former smokers compared with never smokers.

CONCLUSIONS

Cigarette smoking was associated with lower semen volume and total sperm count and higher sperm motility. Smoking cessation might have a restorative effect on semen quality. This finding has important implications for public health research and for understanding the development of abnormal semen quality.

Gaseous pollutant exposure affects semen quality in central China: a cross-sectional study

BACKGROUND

Limited studies have explored the association between gaseous pollutant exposures and male reproductive outcomes, and findings remained inconsistent.

OBJECTIVES

To evaluate the potential association  between gaseous pollutants and semen quality within different exposure windows. MATERIALS AND METHODS: We adopted semen quality data of 1852 subjects who attended the Reproductive Medicine Center of Renmin Hospital at Wuhan University during January 1st, 2013, to August 3rd, 2015. A generalized linear model was employed to assess the relationship between each exposure variable and sperm parameters in different exposure windows.

RESULTS

SO₂ exposure with lag 0-90 days was significantly associated with decreased sperm concentration (β: -1.362; 95% CI: -1.844, -0.879), sperm count (β: -2.979; 95% CI: -4.267, -1.691), and PR (β: -0.551; 95% CI: -0.710, -0.393). Similar trends were observed for SO₂ exposure with three other key periods (lag 0-9, 10-14, and 70-90 days). NO₂ exposure with lag 0-90 days was also associated with decreased sperm concentration (β: -0.517; 95% CI: -1.006, -0.027), sperm count (β: -1.914; 95% CI: -3.214, -0.615), and PR (β: -0.264; 95% CI: -0.425, -0.102). No relationship between gaseous pollutant exposure and ejaculate volume was observed in any exposure window.

DISCUSSION AND CONCLUSION

Our study indicated a strong adverse effect of gaseous pollutants on semen quality outcomes during the sperm development. Gaseous pollution exposure appeared to be more detrimental in the initial phase of spermatogenesis.

Occupational manganese exposure, reproductive hormones, and semen quality in male workers: A cross-sectional study

It has been found that exposure to manganese (Mn) could induce reproductive dysfunction, but its occupational risk in male workers is unclear. This study aims to assess the association of occupational Mn exposure with reproductive hormones and semen quality in a cross-sectional study. Urinary Mn, semen quality, and reproductive hormones were explored in 84 male workers occupationally exposed to Mn and 92 referents. Multiple linear regression analyses were used to assess the relationship. Urinary Mn levels in Mn-exposed workers ranged from 0.56 to 34.25 µg/L, and the average level was 15.92 ± 8.49 µg/L. Compared with the control group, gonadotropin-releasing hormone (GnRH) levels and luteinizing hormone (LH) levels increased significantly and the levels of testosterone (TSTO) decreased significantly in the Mn-exposed group. There was a significant positive linear association between urinary Mn and GnRH and LH, while the linear association between urinary Mn and TSTO was negative. Sperm progressive motility and total motility decreased significantly in the Mn-exposed group. There was a significantly negative linear association between urinary Mn and sperm progressive motility and total motility. In conclusion, occupational Mn exposure was inversely associated with reproductive health of male workers, resulting in the abnormality of hormones secretion and decrease of sperm motility.

Paternal lifestyle factors in relation to semen quality and in vitro reproductive outcomes

This prospective-cohort study aimed at investigating the influence of paternal lifestyle factors on semen parameters and intracytoplasmic sperm injection (ICSI) outcomes. The influence of paternal lifestyle factors on seminal quality and ICSI outcomes was investigated in male patients undergoing conventional semen analysis. Cigarette smoking negatively influenced semen volume (B: -0.417, slope: 1.570, p = 0.047), sperm count/ml (B: -7.363, slope: 52.298, p = 0.014), total sperm count (B: -4.43, slope: 178.165, p = 0.023), total motile sperm count (B: -1.38, slope: 100.276, p = 0.045) and SDF (B: 0.014, slope: 9.767, p = 0.033). Alcohol consumption negatively influenced sperm count/ml (B: -12.527, slope: 42.255, p = 0.040) and sperm DNA fragmentation (B: 5.833, slope: 9.680, p = 0.002). There were no significant influences of other paternal lifestyle factors. Cigarette smoking negatively influenced the fertilisation rate (B: -1.349, slope: 21.950, p = 0.039) and the blastocyst formation rate (B: -14.244, slope: 28.851, p = 0.025). Alcohol consumption negatively influenced fertilisation rate (B: -3.617, slope: 20.138, p = 0.041) and blastocyst formation rate (B: -34.801, slope: 30.044, p = 0.042). Cigarette smoking and alcohol consumption appear to reduce semen quality, fertilisation and blastocyst formation rates; thus, it would be wise to recommend that male partners reconsider their lifestyle during in vitro reproduction treatment.

[Environment and lifestyle: Impacts on male fertility?]

In this last century, an increase of men infertility has been registered. It has been suggested that environmental factors could a negative impact over sperm quality. Among these factors, impact of environmental toxicant has been spread by media. In this review of scientific literature, we identify several environmental factors that could impact men fertility in a negative way. These factors are tobacco, marijuana, weight, body mass index, heat, nutritional state, electromagnetic waves and altitude. For each of these factors, the impact over men fertility, their mechanism, as well their influence over the use of Assisted Reproductive Technics are reported.

Relationships between total testicular volume, reproductive parameters and surrogate measures of adiposity in men presenting for couple's infertility

The objective of this study was to investigate the relationships between total testicular volume (TTV), reproductive parameters and adiposity measures: body mass index, waist circumference and waist-to-height ratio. Semen analysis was performed, and reproductive hormone levels were measured in 2,672 male patients (mean age 32.6) due to couple's infertility. Significant, positive correlations between semen parameters and the TTV were found. Gonadotrophins were negatively related to the TTV, and testosterone was not related to the TTV. Three anthropometric parameters were negatively correlated to the total sperm count, and sperm concentration seen in men with a TTV of ≤46 ml. In the case of a TTV >46 ml, only the semen volume was inversely correlated with WC and WHtR. These changes occurred from a WHtR ≥0.56, WC ≥102 cm and BMI ≥29 and were more pronounced between WHtR and the TTV. Adiposity was associated with a significant testosterone level decline but did not have a major impact on the gonadotrophin levels. This study shows the divergent results in sperm parameters in different TTV groups in the presence of central adiposity.

Impact of alcohol and cigarette smoking consumption in male fertility potential: Looks at lipid peroxidation, enzymatic antioxidant activities and sperm DNA damage

Alcohol intake and cigarette smoking are the major lifestyle factors with negative impact on fertility. We were interested to evaluate the negative impact of these factors on oxidative stress (OS), enzymatic antioxidant activity (EAO) of spermatozoa and on its DNA damage. This study included 108 male infertile patients with normal range of sperm conventional parameters but with unexplained infertility in assisted reproductive technologies programme. Firstly, OS was analysed based on lipid peroxidation (MDA) and EAO which included catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR). Secondly, we evaluated DNA fragmentation by TUNEL assay and chromatin decondensation by aniline blue colouration. The whole lot was divided into four groups: control (nonalcoholic and nonsmoker patients), alcohol group, smoking group and alcohol-smoking group. The results showed, in three last groups compared to control an increased CAT, SOD and GR activities with high MDA level especially in smoking and alcohol-smoking group. The latter showed the highest values of DNA fragmentation and chromatin decondensation (31% and 39%) to exceed DNA damage normal range. Indeed, smoking and alcohol intake lead to increase EAO due to long-term unbalanced antioxidant/oxidation ratio with high OS which cause consequently sperm DNA damage calling in need by urgency to change the lifestyle behaviour.

Decline of semen quality among Chinese sperm bank donors within 7 years (2008-2014)

Semen from 5210 sperm bank donors was analyzed and trends in semen quality were evaluated at Shandong Human Sperm Bank between 2008 and 2014. After 2-7 days of abstinence, semen samples were collected. Measurements of semen volume, sperm concentration, sperm forward motility, and total sperm count were performed. There were significant declining trends in semen volume, sperm concentration, sperm forward motility, and total sperm count. Our results indicate that the quality of semen in this cohort of sperm donors had decreased during the study period.

From sperm to offspring: Assessing the heritable genetic consequences of paternal smoking and potential public health impacts

Individuals who smoke generally do so with the knowledge of potential consequences to their own health. What is rarely considered are the effects of smoking on their future children. The objective of this work was to review the scientific literature on the effects of paternal smoking on sperm and assess the consequences to offspring. A literature search identified over 200 studies with relevant data in humans and animal models. The available data were reviewed to assess the weight of evidence that tobacco smoke is a human germ cell mutagen and estimate effect sizes. These results were used to model the potential increase in genetic disease burden in offspring caused by paternal smoking, with specific focus on aneuploid syndromes and intellectual disability, and the socioeconomic impacts of such an effect. The review revealed strong evidence that tobacco smoking is associated with impaired male fertility, and increases in DNA damage, aneuploidies, and mutations in sperm. Studies support that these effects are heritable and adversely impact the offspring. Our model estimates that, with even a modest 25% increase in sperm mutation frequency caused by smoke-exposure, for each generation across the global population there will be millions of smoking-induced de novo mutations transmitted from fathers to offspring. Furthermore, paternal smoking is estimated to contribute to 1.3 million extra cases of aneuploid pregnancies per generation. Thus, the available evidence makes a compelling case that tobacco smoke is a human germ cell mutagen with serious public health and socio-economic implications. Increased public education should be encouraged to promote abstinence from smoking, well in advance of reproduction, to minimize the transmission of harmful mutations to the next-generation.

Decline in semen quality among 30,636 young Chinese men from 2001 to 2015

OBJECTIVE

To provide information of semen quality among young Chinese men in the past 15 years.

DESIGN

Retrospective cross-sectional study.

SETTING

Sperm bank.

PATIENT(S)

A total of 30,636 young adult men who applied to be sperm donors at the Hunan Province Human Sperm Bank of China in 2001-2015 were included in the study.

INTERVENTION(S)

Physical examination and analysis of blood and semen samples.

MAIN OUTCOME MEASURE(S)

Semen parameters, such as semen volume, sperm concentration, total sperm count, progressively motile sperm count, sperm progressive motility, sperm morphology, and round cells.

RESULT(S)

Many of the semen parameters showed a decreasing trend over the 15-year observation period. The sperm concentration and percentage of sperm with normal morphology decreased from 68 × 10⁶/mL to 47 × 10⁶/mL and from 31.8% to 10.8%, respectively. Although sperm progressive motility showed irregular variation, the progressively motile sperm count decreased from 34 × 10⁶ to 21 × 10⁶ over the 15-year period. Furthermore, the rate of qualified donors fell from 55.78% in 2001 to 17.80% in 2015, and the rate for 2015 was approximately threefold lower than the corresponding rates in 2001.

CONCLUSION(S)

The semen quality among young Chinese men has declined over a period of 15 years, especially in terms of sperm concentration, total sperm count, sperm progressive motility, and normal morphology.

Evaluation of semen quality in 1808 university students, from Wuhan, Central China

The aim of this study was to evaluate the semen quality of university students in Wuhan, the largest city in the world in terms of the number of university students. All student sperm donors recorded in the Hubei Province Human Sperm Bank from 1 March 2010 to 31 December 2013 were screened. At last, a total of 3616 semen samples from 1808 university student sperm donors were eligible and retrospectively analyzed. Each donor's semen parameters were averaged over two samples and compared with the World Health Organization criteria, and a generalized linear regression model was used to examine several determinants of semen quality. We found that the mean and median values were 3.0 ml and 2.8 ml for semen volume, 50.2 × 10⁶ ml⁻¹ and 50.0 × 10⁶ ml⁻¹ for sperm concentration, 148.1 × 10⁶ and 142.1 × 10⁶ for total sperm count, and 58.6% and 60.0% for total sperm motility. About 85.0% of donors had parameters that were all normal. Season and duration of abstinence were critical factors affecting semen quality. We also found a decrease in sperm concentration during the 4 years observation; however, this may not be a strong evidence to confirm the declining trend of semen quality. In conclusion, semen quality of university students in Wuhan was not optimal and should be paid high attention, long-term observation and further study should be carried out to confirm the present situation.

Semen quality in adult male survivors 5 years after the 2008 Wenchuan earthquake

The influence of the Wenchuan earthquake on semen quality of adult male survivors is unclear. We investigated the semen quality included 673 male survivors from the worse-affected counties in the earthquake between Aug 2008 and July 2013. Semen parameters including pH, volume, concentration, motility and morphology were measured according to the World Health Organization (WHO) criteria. Kruskal-Wallis analysis of variance was used to examine the statistical differences between years, and a logistic regression was used to analyse the impacts caused by earthquake on the changes of semen quality. We found the medians (5th and 95th) were 2.5 ml (0.6-5.5) for semen volume, 59.0 × 10⁶  ml^-1 [(13.0-133.0)] × 10⁶  ml^-1 for semen concentration, 46% (13-64%) for sperm progressive motility and 3.0% (0-17.5%) for normal morphology for adult male survivors. Semen concentration, the percentage of sperm progressive motility, total motility and sperm normal morphology were all decreased in the first 3 years, and the differences among years 1, 2 and 3 were significant except the percentage of sperm progressive motility (P < 0.05). The casualties and heavy housing damage caused by earthquake had a negative effect on semen quality. The main findings will provide further diagnosis and therapy basis of male fertility by data, for affected populations in the earthquake.

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

OBJECTIVE

Approximately 37% of men of reproductive age smoke cigarettes, with Europe having the highest tobacco use among all the World Health Organization (WHO) regions. Toxins from tobacco smoking can potentially affect sperm development and function, with a negative effect on semen parameters. Given the high prevalence of smoking and recent changes in the WHO laboratory methods for the examination of human semen, the role of this exposure in face of new WHO methods needs to be clarified.

EVIDENCE ACQUISITION

We conducted a systematic review, followed by a meta-analysis, to determine whether cigarette smoking affects human semen parameters. PubMed, Saint Joseph's University Discover, and Google Scholar were used to identify relevant studies published after release of the latest WHO methods for laboratory evaluation of human semen. Participants were from fertility/urologic clinics and andrology laboratories. The outcome measures were semen volume, sperm concentration, motility, and morphology, the parameters usually used in clinical settings to assess fertility.

EVIDENCE SYNTHESIS

Twenty studies with 5865 participants were included in the meta-analysis. Exposure to cigarette smoking was associated with reduced sperm count (mean difference [MD]: -9.72×10⁶/ml; 95% confidence interval [CI], -13.32 to -6.12), motility (MD: -3.48%; 95% CI, -5.53 to -1.44), and morphology (MD: -1.37%; 95% CI, -2.63 to -0.11). Subgroup analyses indicated that effect size was higher in infertile men than in the general population and in moderate/heavy smokers than in mild smokers. The overall effect size on semen volume, sperm count, and motility remained similar when 2010 and earlier WHO manuals were used for semen analysis but was lower with regard to sperm morphology.

CONCLUSIONS

Our results suggest that cigarette smoking has an overall negative effect on semen parameters. The latest WHO laboratory methods for the examination of human semen had a minimal impact on the magnitude of effect size, thus confirming the observed negative effect of smoking on conventional semen parameters.

PATIENT SUMMARY

A new systematic review and meta-analysis comprising 5865 men shows that cigarette smoking is associated with reduced sperm count and motility. Deterioration of semen quality is more pronounced in moderate and heavy smokers.

Sperm DNA damage-the effect of stress and everyday life factors

The clinical significance of sperm DNA damage lies in its association with natural conception rates and also might have a serious consequence on developmental outcome of the newborn. The aim of the present study is to determine whether stress and everyday life factors are associated with sperm DNA damage in adult men. The study population consisted of 286 men who attended the infertility clinic for diagnostic purposes and who had normal semen concentration of 20-300 m ml(-1) or with slight oligozoospermia (semen concentration of 15-20 m ml(-1)) (WHO, 1999). Participants were interviewed and provided a semen sample. The sperm chromatin structure assay was assessed using flow cytometry. In the present study, we found evidence for a relationship between sperm DNA damage parameters and everyday life factors. High and medium level of occupational stress and age increase DNA fragmentation index (P=0.03, P=0.004 and P=0.03, respectively). Other lifestyle factors that were positively associated with percentage of immature sperms (high DNA stainability index) included: obesity and cell phone use for more than 10 years (P=0.02 and P=0.04, respectively). Our findings indicate that stress and lifestyle factor may affect sperm DNA damage. Data from the present study showed a significant effect of age, obesity, mobile phone radiation and occupational stress on sperm DNA damage. As DNA fragmentation represents an extremely important parameter indicative of infertility and potential outcome of assisted reproduction treatment, and most of the lifestyle factors are easily modifiable, the information about factors that may affect DNA damage are important.

The reference values for semen parameters of 1213 fertile men in Guangdong Province in China

Semen samples were collected from 1213 fertile men whose partners had a time-to-pregnancy (TTP) ≤12 months in Guangdong Province in Southern China, and semen parameters including semen volume, sperm concentration, total counts, motility, and morphology were evaluated according to the World Health Organization (WHO) 2010 guideline. All semen parameters analyzed were normal in ~62.2% of the total samples, whereas ~37.8% showed at least one of the semen parameters below normal threshold values. The fifth centiles (with 95% confidence intervals) were 1.3 (1.2–1.5) ml for semen volume, 20 × 10⁶ (18×10⁶–20×10⁶) ml⁻¹ for sperm concentration, 40 × 10⁶ (38×10⁶–44×10⁶) per ejaculate for total sperm counts, 48% (47%–53%) for vitality, 39% (36%–43%) for total motility, 25% (23%–27%) for sperm progressive motility, 5.0% (4%–5%) for normal morphology. The pH values ranged from 7.2 to 8.0 with the mean ± standard deviation at 7.32 ± 0.17. No effects of age and body mass index were found on semen parameters. Occupation, smoking and alcohol abuse, varicocele appeared to decrease semen quality. Sperm concentration, but not sperm morphology, is positively correlated with TTP, whereas vitality is negatively correlated with TTP. Our study provides the latest reference values for the semen parameters of Chinese fertile men in Guangdong Province, which are close to those described in the new WHO guidelines (5^th Edition).

Associations between occupation exposure to Formaldehyde and semen quality, a primary study

Formaldehyde (FA), a ubiquitous environmental pollutant, has long been suspected of having male reproductive toxicity. However, FA male reproductive toxicity was inconclusive due to dearth of human studies. Therefore, we sought to investigate whether occupational exposure to FA affects semen quality. Semen quality including five conventional parameters and seven kinematics parameters were compared between 114 male workers occupationally exposed to FA and 76 referents. FA exposure index (FEI) was measured and calculated. Our results showed that sperm progressive motility, total sperm motility, VCL, VSL and VAP were statistically significant decreased in FA exposure workers compared with the referents. Moreover, FEI was significantly negative associated with sperm progressive motility (β = -0.19, P = 0.01) and total sperm motility (β = -0.23, P = 0.004). In addition, a significant elevated risk of abnormal sperm progressive motility were observed in both low- (OR = 2.58; 95% CI: 1.11-5.97) and high-FA-exposed group (OR = 3.41; 95% CI: 1.45-7.92) respectively. Furthermore, a significant increased risk was also estimated for abnormal total sperm motility in both low- (OR = 3.21; 95% CI: 1.24-8.28) and high-FA-exposed group (OR = 4.84; 95% CI: 1.83-12.81) respectively. In conclusion, our study revealed the adverse effects of FA occupation exposure on semen quality, especially on sperm motion parameters.

Lifestyles Associated With Human Semen Quality: Results From MARHCS Cohort Study in Chongqing, China

Decline of semen quality in past decades is suggested to be potentially associated with environmental and sociopsychobehavioral factors, but data from population-based cohort studies is limited. The male reproductive health in Chongqing College students (MARHCS) study was established in June 2013 as a perspective cohort study that recruited voluntary male healthy college students from 3 universities in Chongqing. The primary objectives of the MARHCS study are to investigate the associations of male reproductive health in young adults with sociopsychobehavioral factors, as well as changes of environmental exposure due to the relocation from rural campus (in University Town) to metro-campus (in central downtown). A 93-item questionnaire was used to collect sociopsychobehavioral information in manner of interviewer-interviewing, and blood, urine and semen samples were collected at the same time. The study was initiated with 796 healthy young men screened from 872 participants, with a median age of 20. About 81.8% of this population met the WHO 2010 criteria on semen quality given to the 6 routine parameters. Decreases of 12.7%, 19.8%, and 17.0%, and decreases of 7.7%, 17.6%, and 14.7% in total sperm count and sperm concentration, respectively, were found to be associated with the tertiles of accumulated smoking amount. Fried food consumption (1-2  times/wk or ≥3  times/wk vs nonconsumers) was found to be associated with decreased total sperm count (10.2% or 24.5%) and sperm concentration (13.7% or 17.2%), respectively. Coffee consumption was found to be associated with increased progressive and nonprogressive motility of 8.9% or 15.4% for subjects consuming 1-2  cups/wk or ≥3  cups/wk of coffee, respectively. Cola consumption appeared an association with decreased semen volume at 4.1% or 12.5% for 1-2  bottles/wk or ≥3  bottles/wk. A cohort to investigate the effects of environmental/sociopsychobehavioral factors act on semen quality was successfully set up. We found smoking, coffee/cola/fried foods consumption to be significantly associated with semen quality from the baseline investigation.

The impact of male overweight on semen quality and outcome of assisted reproduction

It is well-documented that male overweight and obesity causes endocrine disorders that might diminish the male reproductive capacity; however, reports have been conflicting regarding the influence of male body mass index (BMI) on semen quality and the outcome of assisted reproductive technology (ART). The aim of this study was to investigate whether increased male BMI affects sperm quality and the outcome of assisted reproduction in couples with an overweight or obese man and a non-obese partner. Data was prospectively collected from 612 infertile couples undergoing ART at a Danish fertility center. Self-reported information on paternal height and weight were recorded and BMI was calculated. The men were divided into four BMI categories: underweight BMI < 20 kg m⁻², normal BMI 20–24.9 kg m⁻², overweight BMI 25–29.9 kg m⁻² and obese BMI > 30 kg m⁻². Conventional semen analysis was performed according to the World Health Organization guideline and sperm DNA integrity was analyzed by the Sperm Chromatin Structure Assay (SCSA). No statistically significant effect of male BMI was seen on conventional semen parameters (sperm concentration, total sperm count, seminal volume and motility) or on SCSA-results. Furthermore, the outcome of ART regarding fertilization rate, number of good quality embryos (GQE), implantation and pregnancy outcome was not influenced by the increasing male BMI.

Air pollution and quality of sperm: a meta-analysis

Context:

Air pollution is common in all countries and affects reproductive functions in men and women. It particularly impacts sperm parameters in men. This meta-analysis aimed to examine the impact of air pollution on the quality of sperm.

Evidence Acquisition:

The scientific databases of Medline, PubMed, Scopus, Google scholar, Cochrane Library, and Elsevier were searched to identify relevant articles published between 1978 to 2013. In the first step, 76 articles were selected. These studies were ecological correlation, cohort, retrospective, cross-sectional, and case control ones that were found through electronic and hand search of references about air pollution and male infertility. The outcome measurement was the change in sperm parameters. A total of 11 articles were ultimately included in a meta-analysis to examine the impact of air pollution on sperm parameters. The authors applied meta-analysis sheets from Cochrane library, then data extraction, including mean and standard deviation of sperm parameters were calculated and finally their confidence interval (CI) were compared to CI of standard parameters.

Results:

The CI for pooled means were as follows: 2.68 ± 0.32 for ejaculation volume (mL), 62.1 ± 15.88 for sperm concentration (million per milliliter), 39.4 ± 5.52 for sperm motility (%), 23.91 ± 13.43 for sperm morphology (%) and 49.53 ± 11.08 for sperm count.

Conclusions:

The results of this meta-analysis showed that air pollution reduces sperm motility, but has no impact on the other sperm parameters of spermogram.

Consistent age-dependent declines in human semen quality: a systematic review and meta-analysis

Reduced fertility typically occurs among women in their late 30s, but increasing evidence indicates that advanced paternal age is associated with changes in reproduction as well. Numerous studies have investigated age-based declines in semen traits, but the impact of paternal age on semen parameter values remains inconclusive. Using data from 90 studies (93,839 subjects), we conducted a systematic review and meta-analysis to quantify the effect of male age on seven ejaculate traits (semen volume, sperm concentration, total sperm count, morphology, total motility, progressive motility and DNA fragmentation). Age-associated declines in semen volume, percentage motility, progressive motility, normal morphology and unfragmented cells were statistically significant and results generally seemed to be robust against confounding factors. Unexpectedly, sperm concentration did not decline with increasing male age, even though we found that sperm concentration declined over time. Our findings indicate that male age needs more recognition as a potential contributor to the negative pregnancy outcomes and reduced offspring health associated with delayed first reproduction. We suggest that greater focus on collection of DNA fragmentation and progressive motility in a clinical setting may lead to better patient outcomes during fertility treatments of aging couples.