Regional differences in semen quality in Europe

Protective effects of L-theanine and dihydromyricetin on reproductive function in male mice under heat stress

Heat stress can impair the male reproductive function. L-Theanine and dihydromyricetin have biological activities against heat stress; however, their effects on reproductive function in heat-stressed males are unclear. In this study, male mice were given L-theanine, dihydromyricetin, or a combination of both for 28 days, followed by 2 h of heat stress daily for 7 days. All interventions alleviated heat stress-induced testicular damage, improving the testicular organ index, sperm density, acrosome integrity, sperm deformity rate, and hormone levels. Treatment increased the antioxidant enzyme activity and decreased the markers of oxidative and inflammatory stress in the testes. A combination dose of 200 + 200 mg kg-1 d-1 showed the best protective effect. The potential mechanism involves the regulation of HSP27 and HSP70, which regulate the levels of reproductive hormones through the StAR/Cyp11a1/Hsd3b1/Cyp17a1/Hsd17b3 pathway, alleviate inflammation and oxidative stress through the P38/NF-κB/Nrf2/HO-1 pathway, and regulate the Bcl-2/Fas/Caspase3 apoptotic pathway. Overall, L-theanine and dihydromyricetin may play a protective role against heat stress-induced reproductive dysfunction, suggesting their potential use in heat stress-resistant foods.

Deteriorating Semen Quality: The Role of the Environment

Since the end of the last century, several reports have suggested that semen quality is declining, especially in Western countries. Furthermore, cross-sectional studies using similar protocols have suggested regional differences in semen quality of young and fertile men. Reasons for these regional differences and local adverse trends in semen quality are unknown, but environmental factors are suspected to have a role. Besides adulthood environmental exposures, those occurring during testicular development may also affect semen quality. Longitudinal follow-up studies and mixture risk analyses are needed to study the effect of fetal, childhood, and adult life environment on semen quality.

Geographic Differences in Semen Quality among a Cohort of American Men Using Mail-in Sperm Testing Kits

PURPOSE

To evaluate the relationship between regional geography and sperm parameters in a cohort of American men using at-home mail-in semen collection kits with no previous self-reported history of male factor infertility.

MATERIALS AND METHODS

In this study, 5,822 men from six different regions of the United States (Northeast, Southeast, Midwest, West, Pacific, and Southwest) who self-requested semen analysis between 2019 and 2021 were enrolled.

RESULTS

Across the entire cohort, the mean sperm concentration was 43.79±55.43 ×106 sperm/mL; total sperm count 138.93±149.96 ×106 sperm/mL; total motile sperm 54.73±81.90 ×106/ejaculate; total motility 30.18%±22.87%; progressive motility 21.61%±17.32%; sperm with normal morphology 8.79%±8.87%. Patients from the West region displayed lower median sperm concentration, total motile sperm, and total motility than men from the other four regional areas. A lower median total sperm count, and lower median progressive motility were also detected among patients in the Southwest region. Conversely, higher results were detected in patients from the Midwest (higher median total motile sperm, total and motility) and from the Northeast (higher median sperm concentration and total sperm count) regions. Men from the Southeast (OR, 1.3168; 95% CI, 1.1142-1.5563) and Southwest (OR, 1.3145; 95% CI, 1.0735-1.6096) regions were more likely to have oligozoospermia than those living elsewhere.

CONCLUSIONS

This study provides the most comprehensive and up-to-date report on semen parameter variability among a cohort of men living in six different regions of the continental USA. This study will pave the way into a deeper discussion of the interplay between geography, social determinants of fertility care and semen quality.

Trend of change of sperm count and concentration over the last two decades: A systematic review and meta-regression analysis

BACKGROUND

Since the 1970s, several studies found that sperm concentration (SC) and total sperm count (TSC) constantly worsened over time, mainly in high-income countries.

OBJECTIVES

To evaluate whether the decreasing trend in sperm count is continuing in Western European countries and USA, we performed a systematic review and meta-regression analysis.

MATERIALS AND METHODS

Embase and Pubmed/Medline were searched papers published in English in the 2000-2020 period limiting the search to data collected in the USA and Western European countries.

RESULTS

We identified 62 articles and pooled information on 24,196 men (range 10-2,523), collected from 1993 to 2018. Considering all the studies, random-effects meta-regression analyses showed no significant trend for SC (slope per year -0.07 mil/mL, p-value = 0.86). Negative trends of SC were detected in Scandinavian countries (slope per year -1.11 mil/mL, 95% CI: -2.40 to +0.19; p-value = 0.09), but the findings were statistically not significant. No significant trends of SC were detected in Central Europe (slope per year +0.23, 95% CI -2.51 to +2.96; p-value = 0.87), the USA (slope per year +1.08, 95% CI -0.42 to +2.57; p-value = 0.16), and Southern Europe (slope per year +0.19, 95% CI -0.99 to +1.37; p-value = 0.75). We have analyzed separately findings from studies including sperm donors, fertile men, young unselected men (unselected men, study mean age < 25 years) and unselected men (unselected men, study mean age ≥ 25 years). No significant trends of SC were observed among sperm donors (slope per year -2.80, 95% CI -6.76 to +1.17; p-value 0.16), unselected men (slope per year -0.23, 95% CI -1.58 to +1.12; p-value 0.73), young unselected men (slope per year -0.49, 95% CI -1.76 to +0.79; p-value 0.45), fertile men (slope per year +0.29, 95% CI -1.09 to +1.67; p-value 0.68).

DISCUSSION AND CONCLUSION

The results of this analysis show no significant trends in SC, in USA, and selected Western European countries.

Global trends in semen quality of young men: a systematic review and regression analysis

PURPOSE

Many studies have reported declines in semen quality mainly focused on total sperm counts (TSC) and sperm concentration (SC), ignoring the importance of progressive motile sperm (PR), total motile sperm (TM), and normal morphological sperm (NM). Therefore, we performed a comprehensive meta-analysis to explore the trend in semen quality of young men.

METHODS

We searched 3 English databases and 4 Chinese databases from January 1980 to August 2022. Random-effect meta-analyses and weighted linear regression models were conducted to perform the trend in semen quality.

RESULTS

Finally, 162 eligible studies including 264,665 men from 28 countries were got between 1978 and 2021. Significant decreases were observed in TSC (- 3.06 million/year, 95% CI - 3.28 to - 2.84), SC (- 0.47 million/ml/year, 95% CI - 0.51 to - 0.43), and PR (- 0.15%/year, 95% CI - 0.20 to - 0.09), and there was an upward trend in TM (0.28%/year, 95% CI 0.24 to 0.32). The results of meta-regression analyses indicated that age, continent, income, WHO criteria, and abstinence time significantly impacted on TSC, SC, PR, and TM. Positive regression coefficients were observed in some categories suggesting that outcomes might not be declining and even increasing in these subgroups.

CONCLUSIONS

Downward trends in semen quality among global young men were observed in our study, including TSC, SC, and PR. But TM did not appear to be trending down or even to be leveling off. More studies are needed to focus on the causes of the declines.

Potential Function of Testicular MicroRNAs in Heat-Stress-Induced Spermatogenesis Disorders

Spermatogenesis is temperature-dependent, and the increase in testicular temperature seriously affects mammalian spermatogenesis and semen quality. In this study, the testicular heat stress model of mice was made with a 43 °C water bath for 25 min, and the effects of heat stress on semen quality and spermatogenesis-related regulators were analyzed. On the 7th day after heat stress, testis weight shrank to 68.45% and sperm density dropped to 33.20%. High-throughput sequencing analysis showed that 98 microRNAs (miRNAs) and 369 mRNAs were down-regulated, while 77 miRNAs and 1424 mRNAs were up-regulated after heat stress. Through gene ontology (GO) analysis of differentially expressed genes and miRNA-mRNA co-expression networks, it was found that heat stress may be involved in the regulation of testicular atrophy and spermatogenesis disorders by affecting cell meiosis process and cell cycle. In addition, through functional enrichment analysis, co-expression regulatory network, correlation analysis and in vitro experiment, it was found that miR-143-3p may be a representative potential key regulatory factor affecting spermatogenesis under heat stress. In summary, our results enrich the understanding of miRNAs in testicular heat stress and provide a reference for the prevention and treatment of heat-stress-induced spermatogenesis disorders.

Reproductive toxicity of combined effects of endocrine disruptors on human reproduction

Confluence of environmental, genetic, and lifestyle variables is responsible for deterioration of human fecundity. Endocrine disruptors or endocrine disrupting chemicals (EDCs) may be found in a variety of foods, water, air, beverages, and tobacco smoke. It has been demonstrated in experimental investigations that a wide range of endocrine disrupting chemicals have negative effects on human reproductive function. However, evidence on the reproductive consequences of human exposure to endocrine disrupting chemicals is sparse and/or conflicting in the scientific literature. The combined toxicological assessment is a practical method for assessing the hazards of cocktails of chemicals, co-existing in the environment. The current review provides a comprehensive overview of studies emphasizing the combined toxicity of endocrine disrupting chemicals on human reproduction. Endocrine disrupting chemicals interact with each other to disrupt the different endocrine axes, resulting in severe gonadal dysfunctions. Transgenerational epigenetic effects have also been induced in germ cells, mostly through DNA methylation and epimutations. Similarly, after acute or chronic exposure to endocrine disrupting chemicals combinations, increased oxidative stress (OS), elevated antioxidant enzymatic activity, disrupted reproductive cycle, and reduced steroidogenesis are often reported consequences. The article also discusses the concentration addition (CA) and independent action (IA) prediction models, which reveal the importance of various synergistic actions of endocrine disrupting chemicals mixtures. More crucially, this evidence-based study addresses the research limitations and information gaps, as well as particularly presents the future research views on combined endocrine disrupting chemicals toxicity on human reproduction.

Temporal trends in sperm count: a systematic review and meta-regression analysis of samples collected globally in the 20th and 21st centuries

BACKGROUND

Numerous studies have reported declines in semen quality and other markers of male reproductive health. Our previous meta-analysis reported a significant decrease in sperm concentration (SC) and total sperm count (TSC) among men from North America-Europe-Australia (NEA) based on studies published during 1981-2013. At that time, there were too few studies with data from South/Central America-Asia-Africa (SAA) to reliably estimate trends among men from these continents.

OBJECTIVE AND RATIONALE

The aim of this study was to examine trends in sperm count among men from all continents. The broader implications of a global decline in sperm count, the knowledge gaps left unfilled by our prior analysis and the controversies surrounding this issue warranted an up-to-date meta-analysis.

SEARCH METHODS

We searched PubMed/MEDLINE and EMBASE to identify studies of human SC and TSC published during 2014-2019. After review of 2936 abstracts and 868 full articles, 44 estimates of SC and TSC from 38 studies met the protocol criteria. Data were extracted on semen parameters (SC, TSC, semen volume), collection year and covariates. Combining these new data with data from our previous meta-analysis, the current meta-analysis includes results from 223 studies, yielding 288 estimates based on semen samples collected 1973-2018. Slopes of SC and TSC were estimated as functions of sample collection year using simple linear regression as well as weighted meta-regression. The latter models were adjusted for predetermined covariates and examined for modification by fertility status (unselected by fertility versus fertile), and by two groups of continents: NEA and SAA. These analyses were repeated for data collected post-2000. Multiple sensitivity analyses were conducted to examine assumptions, including linearity.

OUTCOMES

Overall, SC declined appreciably between 1973 and 2018 (slope in the simple linear model: -0.87 million/ml/year, 95% CI: -0.89 to -0.86; P < 0.001). In an adjusted meta-regression model, which included two interaction terms [time × fertility group (P = 0.012) and time × continents (P = 0.058)], declines were seen among unselected men from NEA (-1.27; -1.78 to -0.77; P < 0.001) and unselected men from SAA (-0.65; -1.29 to -0.01; P = 0.045) and fertile men from NEA (-0.50; -1.00 to -0.01; P = 0.046). Among unselected men from all continents, the mean SC declined by 51.6% between 1973 and 2018 (-1.17: -1.66 to -0.68; P < 0.001). The slope for SC among unselected men was steeper in a model restricted to post-2000 data (-1.73: -3.23 to -0.24; P = 0.024) and the percent decline per year doubled, increasing from 1.16% post-1972 to 2.64% post-2000. Results were similar for TSC, with a 62.3% overall decline among unselected men (-4.70 million/year; -6.56 to -2.83; P < 0.001) in the adjusted meta-regression model. All results changed only minimally in multiple sensitivity analyses.

WIDER IMPLICATIONS

This analysis is the first to report a decline in sperm count among unselected men from South/Central America-Asia-Africa, in contrast to our previous meta-analysis that was underpowered to examine those continents. Furthermore, data suggest that this world-wide decline is continuing in the 21st century at an accelerated pace. Research on the causes of this continuing decline and actions to prevent further disruption of male reproductive health are urgently needed.

Exposure to ambient particulate matter affects semen quality: A case study in Wenzhou, China

BACKGROUND

Particulate matter (PM), including PM_2.5 (PM ≤ 2.5 µm in aerodynamic diameter) and PM₁₀ (PM ≤ 10 µm in aerodynamic diameter), is a component of air pollutants, which is linked to semen quality. However, the available evidence of association needs to be strengthened, and some studies have conflicting results.

OBJECTIVES

To evaluate the potential impacts of PM on semen quality during the full (0-90 days before semen examination) and three key sperm development windows (0-9, 10-14, and 70-90 days before semen examination).

METHODS

We included 1494 infertile men in the main urban area in Wenzhou, China, who had undergone semen examinations for fertility between 2014 and 2019. The impacts were assessed by multivariable linear regression models.

RESULTS

Overall, during the full sperm development window, PM_2.5 and PM₁₀ exposures were associated with declined progressive sperm motility (%) (β: -0.6; 95% confidence intervals (CIs): -1.07, -0.13 and -0.46; -0.59, -0.33) and total sperm motility (%) (-1.95; -2.67, -1.23 and -1.32; -1.82, -0.82), and associated with increased sperm concentration (10⁶ /ml) (0.02; 0.006, 0.023 and 0.007; 0.001, 0.013) and total sperm number (10⁶ ) (0.02; 0.01, 0.03 and 0.011; 0.004, 0.017). Furthermore, only PM_2.5 exposure during the 10-14 days window was significantly associated with declined progressive motility (%) (-0.207; -0.395, -0.023).

CONCLUSIONS

During the full sperm development window, PM exposure has an adverse impact on sperm motility and positive impacts on sperm concentration and total sperm number. The adverse impact was more severe in the 10-14 days window.

Impact of Nanoparticles on Male Fertility: What Do We Really Know? A Systematic Review

The real impact of nanoparticles on male fertility is evaluated after a careful analysis of the available literature. The first part reviews animal models to understand the testicular biodistribution and biopersistence of nanoparticles, while the second part evaluates their in vitro and in vivo biotoxicity. Our main findings suggest that nanoparticles are generally able to reach the testicle in small quantities where they persist for several months, regardless of the route of exposure. However, there is not enough evidence that they can cross the blood-testis barrier. Of note, the majority of nanoparticles have low direct toxicity to the testis, but there are indications that some might act as endocrine disruptors. Overall, the impact on spermatogenesis in adults is generally weak and reversible, but exceptions exist and merit increased attention. Finally, we comment on several methodological or analytical biases which have led some studies to exaggerate the reprotoxicity of nanoparticles. In the future, rigorous clinical studies in tandem with mechanistic studies are needed to elucidate the real risk posed by nanoparticles on male fertility.

Effects of virtual reality erotica on ejaculate quality of sperm donors: a balanced and randomized controlled cross-over within-subjects trial

BACKGROUND

Previous research has shown that the type and duration of erotic material that men have access to during masturbation can influence semen parameters. To our knowledge, the use of virtual reality (VR) headsets to present erotica has not previously been studied. We reasoned that, because VR can provide a more immersive experience to the user, semen parameters of masturbatory ejaculates may be altered.

METHODS

This study had a balanced and randomized controlled cross-over within-subjects design. 504 ejaculates were collected from 63 sperm donors at 4 locations in Denmark. During masturbation each donor was instructed to observe erotic material either on a touch screen monitor or using a VR headset. The order of each pair of within-subject treatments was randomized by the throw of a dice. Anonymized data were analysed with linear mixed and piecewise structural equation models.

RESULTS

Both abstinence period and VR-use influenced the total number of motile spermatozoa ejaculated. For short abstinence periods, VR-use increased the number of motile sperm in the ejaculate. However, the difference between VR and non-VR ejaculates decreased as abstinence period increased such that there was no difference at the mean abstinence period of 58 h. For longer abstinence periods, total motile sperm counts were lower, on average, when men used VR compared to those that did not.

CONCLUSION

The use of VR headsets to view erotica had a strong positive effect on the number of motile sperm in an ejaculate when the donor's abstinence time was short (< 24 h). VR-use could improve the ejaculate quality of men who are asked to provide samples after a short period of abstinence, such as men in infertile partnerships producing samples for ART or cancer patients depositing sperm before treatment.

TRIAL REGISTRATION

Trial retrospectively registered on 13 July 2022 at ClinicalTrials.gov. Identifier: NCT05457764.

Geographic variation in semen parameters from data used for the World Health Organization semen analysis reference ranges

OBJECTIVE

To study geographic variations in sperm parameters using data from the trials that defined the reference ranges of the World Health Organization 2021 manual.

DESIGN

Retrospective evaluation of the data used to define the World Health Organization reference ranges.

SETTING

Not applicable.

PATIENT(S)

Data from 11 studies, including 3,484 participants across 5 continents.

INTERVENTION(S)

The data were divided according to geographic locations.

MAIN OUTCOME MEASURE(S)

Differences in sperm parameters.

RESULT(S)

The semen volume was significantly lower in samples from Asia and Africa than in other regions. The sperm concentration was the lowest in Africa and highest in Australia. The total motile sperm count (TMSC) and total motile progressive sperm count (TMPS) were significantly lower in Africa than in other regions. The TMSC and TMPS in Asia and the United States were significantly lower than in Europe and Australia. The 5th percentile of the sperm concentration was lowest in the United States (12.5 × 10⁶/mL). The 5th percentile for the normal sperm morphology was lowest in the United States (3%) and highest in Asia (5%). The 5th percentile for the TMSC and TMPS were lowest in Africa (TMSC, 15.08 million; TMPS, 12.06 million) and the United States (TMSC, 18.05 million; TMPS, 16.86 million) and highest in Australia (TMSC, 29.61 million; TMPS, 25.80 million).

CONCLUSION(S)

Significant geographic differences in sperm parameters exist, and regional fertility societies should consider adding their own reference ranges on the basis of local experience and treatment outcomes.

Spatiotemporal trends in human semen quality

Over the past four decades, studies of various designs have reported spatial and temporal trends in human semen quality. Several standardized-methodology studies in homogeneous populations that compare specific cities within a country or a continent provide clear evidence of geographical differences in sperm production, even over short distances within the same country. Human sperm production is widely believed to be declining over time, but evidence from the scientific literature is less clear. Studies based on repeated cross-sectional data from a single centre have shown mixed results. Among the numerous retrospective studies conducted in a single centre, only some included homogeneous groups of men and appropriate methods, and most of them suggest a temporal decrease in human sperm production in the geographical areas considered. Conclusions reporting temporal trends in sperm production that came from existing retrospective multicentre studies based on individual semen data and those using means, medians or estimates of sperm production are questionable, owing to intrinsic limitations in the studies performed. Regardless of study design, studies on the percentage of motile or morphologically normal spermatozoa are still limited by the inherent variability in assessment. Overall, available data do not enable us to conclude that human semen quality is deteriorating worldwide or in the Western world, but that a trend is observed in some specific areas. To understand these trends and contrasts in sperm and semen quality, prospective studies should be encouraged and combined with assessment of the male exposome.

Several studies over the past few decades have suggested that sperm quality varies by geographical region and might be subject to a temporal decline worldwide. However, the data supporting these conclusions have come from studies of various methodologies and heterogeneous populations, making them unreliable. In this in-depth Review, Chevrier and colleagues discuss the data surrounding discussion of spatiotemporal trends in semen parameters and consider how these trends and the factors promoting them interact.

The vast literature on human semen quality trends is extremely heterogeneous in terms of the populations studied and study designs, and so these studies have been unable to draw firm conclusions.

Understanding the data around spatiotemporal semen trends requires a focus on the methodological choices and application of criteria to filter findings from the studies with optimal design.

Numerous appropriately designed studies suggest unambiguous geographical contrasts in human sperm production; however, evidence of a decline in sperm production is reliable only in specific populations and cities in which studies with a complete set of quality criteria have been conducted.

By contrast, suggestions of a worldwide drop in human semen quality on the basis of retrospective multicentre studies cannot be substantiated, owing to intrinsic limitations in the studies performed.

Many and varied factors of variation, in particular the diverse modalities of assessment, do not enable us to conclude that clear temporal trends of sperm motility and normal morphology are present.

Progress in our understanding of the highlighted trends and their causal factors requires prospective studies that minimize all known biases combined with the assessment of men’s exposome.

Sperm characteristics in normal and abnormal ejaculates are differently influenced by length of ejaculatory abstinence

BACKGROUND

No association between the length of ejaculatory abstinence (LEA) and semen characteristics has been confirmed. A short LEA has been linked to improved sperm characteristics and a higher pregnancy rate, but its negative influence on sperm chromatin maturity and longevity may adversely affect reproductive outcomes.

OBJECTIVES

We sought to determine the influence of LEA on: (i) semen parameters in normozoospermic and abnormal ejaculates; and (ii) the outcomes of sperm-preparation methods in a large number of sub-fertile men undergoing infertility workups.

MATERIALS AND METHODS

This retrospective registry-based cohort study analyzed the data of 10,674 ejaculates from 7,972 sub-fertile men, who were then segregated into normozoospermic, oligozoospermic, asthenozoospermic, and oligo-asthenozoospermic cohorts. Variations in semen characteristics and post-wash outcomes were studied between 4 LEA intervals across 0-15 days.

RESULTS

An age-adjusted analysis of covariance (ANCOVA) model linked significant increases in ejaculate volume, sperm concentration (except in the oligozoospermic cohort), and total sperm number to an increased LEA (p < 0.05). LEA was negatively associated with motility (except in the asthenozoospermic cohort) and vitality (p < 0.05). Large-headed spermatozoa were less common with an increased LEA only in the oligoasthenozoopermic cohort (p < 0.05). In the normozoospermic cohort, a longer LEA led to fewer sperm with amorphous heads but more sperm with tapered heads and cytoplasmic droplets (p < 0.05). LEA extension resulted in greater sperm DNA fragmentation in the abnormal cohort (p < 0.01). The post-wash sperm concentration and total motile sperm count were significantly improved with a longer LEA in the normozoopsermic cohort (p < 0.05).

DISCUSSION AND CONCLUSION

Considering the findings in this study and existing literature, a generalized recommendation for long LEA has no clinical value. The LEA should be individualized based on the ejaculate profile and the need for specific clinical intervention. This article is protected by copyright. All rights reserved.

Evolution of the WHO "Semen" processing manual from the first (1980) to the sixth edition (2021)

As stated clearly in all editions of the WHO Laboratory Manual for the Examination and Processing of Human Semen, the goal of the manual is to meet the growing needs for the standardization of semen analysis procedures. With constant advances in andrology and reproductive medicine and the advent of sophisticated assisted reproductive technologies for the treatment of infertility, the manual has been continuously updated to meet the need for new, evidence-based, validated tests to not only measure semen and sperm variables but also to provide a functional assessment of spermatozoa. The sixth edition of the WHO manual, launched in 2021, can be freely downloaded from the WHO website, with the hope of gaining wide acceptance and utilization as the essential source of the latest, evidence-based information for laboratory procedures required for the assessment of male reproductive function and health.

An evaluation of changes over time in the semen parameters data used for the World Health Organization semen analysis reference ranges

BACKGROUND

Previous meta-analyses concluded that there is a decline in sperm parameters over time. This conclusion might be incorrect due to inherent biases or focusing only on a single parameter - sperm concentration.

OBJECTIVE

To study trends in sperm parameters over the past twenty years using data from the trials that defined the reference ranges of the World Health Organization manual.

MATERIALS AND METHODS

Retrospective evaluation of the data used to define the World Health Organization reference ranges. The data from 11 studies, including 3589 participants between 1996-2016, were divided into three period groups based on the decade of study. Differences in semen parameters' distribution were presented in boxplot. P-values were calculated by the Kruskal Wallis rank-sum test followed by Dunn post-hoc test. Analyses were conducted using the R programming language.

RESULTS

A small decrease was noted in mean sperm concentrations (88.1 million/ml, 87.6 million/ml and 77.2 million/ml for the first second and third decades respectively) (p<0.01). However, the 5^th percentile of sperm concentration for the third decade was higher than the first or second decades (18 million/ml vs. 14.9 million/ml and 15 million/ml respectively). No significant differences were noted in progressive motility over the years (p = 0.32). The percent of morphologically normal sperm decreased between the first (24.2%) and the second (12.6%) periods of the study (p<0.001) and then increased in the third decade (14.2%) (p<0.01). While TMC declined between the second and third decades (189 million and 153.9 million respectively, p<0.001), at levels unlikely to decrease fertility. However, the 5^th percentile of the TMC remained stable at 24.9, 20.8 and 20.6 million, for the first, second and third decades respectively (p = 0.36).

DISCUSSION AND CONCLUSION AND RELEVANCE

Trends in sperm parameters over the last three decades do not seem to be clinically significant. This article is protected by copyright. All rights reserved.

Sperm mitochondrial DNA copy numbers in normal and abnormal semen analysis: a systematic review and meta-analysis

BACKGROUND

Normal mature sperm have a considerably reduced number of mitochondria which provide the energy required for progressive sperm motility. Literature suggests that disorders of sperm motility may be linked to abnormal sperm mitochondrial number and function.

OBJECTIVES

To summarize the evidence from literature regarding the association of mitochondrial DNA copy numbers and semen quality with a particular emphasis on the spermatozoa motility.

SEARCH STRATEGY

Standard methodology recommended by Cochrane.

SELECTION CRITERIA

All published primary research reporting on the association between mitochondrial DNA copy numbers and semen quality.

DATA COLLECTION AND ANALYSIS

Using standard methodology recommended by Cochrane we pooled results using a random effects model and the findings were reported as a standardised mean difference.

MAIN RESULTS

We included 10 studies. The primary outcome was sperm mitochondrial DNA copy numbers. A meta-analysis including five studies showed significantly higher mitochondrial DNA copy numbers in abnormal semen analysis as compared to normal semen analysis(SMD 1.08, 95% CI 0.74-1.43). Seven studies included in the meta-analysis showed a significant negative correlation between mitochondrial DNA copy numbers and semen parameters. The quality of evidence was assessed as good to very good in 60% of studies.

CONCLUSIONS

Our review demonstrates significantly higher mitochondrial DNA in human sperm cells of men with abnormal semen analysis in comparison to men with normal semen analysis.

Use of paracetamol (acetaminophen) as a nonprescription analgesic and semen quality in young men: A cross-sectional study

BACKGROUND

Paracetamol (acetaminophen) is a frequently used nonprescription analgesic with suggested endocrine-disrupting properties. Epidemiological evidence on the effect of paracetamol on male fecundity is sparse.

OBJECTIVES

To investigate if the use of paracetamol as an oral nonprescription mild analgesic was associated with semen quality in young men.

MATERIALS AND METHODS

This cross-sectional study was based on data from the Fetal Programming of Semen Quality (FEPOS; 2017-2019) cohort of 1058 young men (18-21 years) included in the Danish National Birth Cohort. Participants completed a comprehensive online questionnaire on health behavior including analgesic use and provided a semen sample. Negative binomial regression models were used to estimate the percentage differences (adjusted mean ratios [aMR]) in semen quality characteristics according to paracetamol use (no; yes) and frequency of use (almost never; <1/month; ≥1/month; ≥1/week).

RESULTS

In total, 28% of the 913 participants with available data reported the use of paracetamol within the last 6 months. We found a slightly higher total sperm count (aMR 1.13 95% CI [0.99-1.30]) in users compared to nonusers but other semen characteristics were unaffected. The frequency of use was suggestive of lower total sperm count and morphologically normal sperm cells primarily among users ≥1/week, however, CIs were wide.

DISCUSSION

We were unable to account for the underlying reason for paracetamol use, which may induce confounding by indication. Exposure misclassification due to recall is likely but probably nondifferential due to the participants' young age and unawareness of semen quality. Due to the rapid plasma half-life of paracetamol and few frequent users, it was not possible to conclude on potential high-dose effects.

CONCLUSION

Our findings do not suggest any strong detrimental effect of paracetamol use on semen quality within this sample of young Danish men. However, the effects of high dose and frequent use cannot be excluded.

Impaired semen quality, an increase of sperm morphological defects and DNA fragmentation associated with environmental pollution in urban population of young men from Western Siberia, Russia

Poor sperm morphology and an elevated DNA fragmentation level are considered to be related to spermiogenesis malfunctions as a result of genetic mutations and effects of environmental factors, including industrial pollution. Standardized cross-sectional population studies of sperm morphology defects and sperm DNA fragmentation, especially in regions with increased environmental pollution may be helpful to investigate an influence of industrial pollution and other population-related factors on spermiogenesis process. The aim of present study was to estimate an influence industrial pollution on sperm morphogenesis and sperm DNA fragmentation in men from the general population of the Western Siberia. The Novosibirsk and Kemerovo cities are located to same climatic conditions in Western Siberia but the Kemerovo city is characterized by increased environmental pollution especially by particulate matter (PM). The male volunteers living in Novosibirsk (n = 278) and Kemerovo (n = 258) were enrolled. Percentages of sperm morphological defects are counted after staining native ejaculate smears by Diff-Quick kits. DNA fragmentation was estimated by a SCSA technique. The residents of Kemerovo were characterized by lowered sperm count and sperm motility, elevated DNA fragmentation, poor sperm morphology and increased incidence of morphological effects of head (pyriform, elongated, round, abnormal acrosome and vacuolated chromatine), asymmetrical neck insertion and excess residual cytoplasm. Moreover, elevated DNA fragmentation was associated with lowered sperm count, sperm motility and increased percentages of several sperm morphology defects, with the place of residence affecting the relationships between conventional semen parameters, sperm morphology and DNA fragmentations. Our study suggests that excessive sperm head elongation and impaired acrosome formation can contribute to sperm morphology deterioration in men from polluted areas. Regional features in the relationships between sperm morphology, sperm count and DNA fragmentation were shown, suggesting an importance of studying sperm morphology pattern in men from different regions.

Is Ejaculation Frequency in Men Related to General and Mental Health? Looking Back and Looking Forward

Despite its relevance for human sexuality, literature on potential effects of ejaculation frequency and masturbation on general and mental health outcomes is sparse. Reasons for this knowledge gap include a general lack of interest, but also methodological challenges and still existing superstition. This paper reconciles literature from various fields to extract relevant information on how ejaculation frequency effects general and mental health outcomes. Culture-bound syndromes have been reported in countries still strictly tabooing or condemning masturbation. Masturbatory guilt describes a phenomenon in individuals experiencing a discrepancy between moral standards and own behavior with respect to masturbation. Abstinence is one aspect under study in the area of fertility treatment. Specific time frames and their respective implications on quality of sperm remain inconclusive. Limited temporal resolution capacities hamper the precise study of brain structures directly activated during ejaculation. The relation between ejaculation frequency and hormonal influences remains poorly understood. Future research that specifically addresses ejaculation frequency and potential mental and general health outcomes is needed. In contrast to extracting knowledge as a byproduct from other studies with a different focus, this enables sound study designs and could provide evidence-based results which could then be further discussed and interpreted.

Effectiveness of Pharmacological Intervention Among Men with Infertility: A Systematic Review and Network Meta-Analysis

Background. Infertility is an emerging health issue for men. Comparative efficacy of different pharmacological interventions on male infertility is not clear. The aim of this review is to investigate the efficacy of various pharmacological interventions among men with idiopathic male infertility. All randomized control trials evaluating the effectuality of interventions on male infertility were included for network meta-analysis (NMA) from inception to 31 April 2020, systematically performed using STATA through the random effect model. The protocol was registered at PROSPERO (CRD42020152891). Results. The outcomes of interest were semen and hormonal parameters. Treatment effects (p < 0.05) were estimated through WMD at the confidence interval of 95%. Upon applying exclusion criteria, n=28 RCTs were found eligible for NMA. Results from NMA indicated that consumption of supplements increases sperm concentration levels [6.26, 95% CI 3.32, 9.21] in comparison to SERMs [4.97, 95% CI 1.61, 8.32], hormones [4.14, 95% CI 1.83, 6.46], and vitamins [0.15, 95% CI -20.86, 21.15)] with placebo, whereas the use of SERMs increased percentage sperm motility [6.69, 95% CI 2.38, 10.99] in comparison to supplements [6.46, 95% CI 2.57, 10.06], hormones [3.47, 95% CI 0.40, 6.54], and vitamins [-1.24, 95% CI -11.84, 9.43] with placebo. Consumption of hormones increased the sperm morphology [3.71, 95% CI, 1.34, 6.07] in contrast to supplements [2.22, 95% CI 0.12, 4.55], SERMs [2.21, 95% CI -0.78, 5.20], and vitamins [0.51, 95% CI -3.60, 4.62] with placebo. Supplements boosted the total testosterone levels [2.70, 95% CI 1.34, 4.07] in comparison to SERMs [1.83, 95% CI 1.16, 2.50], hormones [0.40, 95% CI -0.49, 1.29], and vitamins [-0.70, 95% CI -6.71, 5.31] with placebo. SERMs increase the serum FSH levels [3.63, 95% CI 1.48, 5.79] better than hormones [1.29, 95% CI -0.79, 3.36], vitamins [0.03, 95% CI -2.69, 2.76], and supplements [-4.45, 95% CI -7.15, -1.76] in comparison with placebo. Conclusion. This review establishes that all interventions had a significantly positive effect on male infertility. Statistically significant increased sperm parameters were noted in combinations of zinc sulfate (220 mg BID), clomiphene citrate (50 mg BID), and testosterone undecanoate and CoQ10; tamoxifen citrate and FSH were shown to improve the hormonal profile in infertile males.

Whole-Exome Sequencing Analysis of Human Semen Quality in Russian Multiethnic Population

The global trend toward the reduction of human spermatogenic function observed in many countries, including Russia, raised the problem of extensive screening and monitoring of male fertility and elucidation of its genetic and ethnic mechanisms. Recently, whole-exome sequencing (WES) was developed as a powerful tool for genetic analysis of complex traits. We present here the first Russian WES study for identification of new genes associated with semen quality. The experimental 3 × 2 design of the WES study was based on the analysis of 157 samples including three ethnic groups—Slavs (59), Buryats (n = 49), and Yakuts (n = 49), and two different semen quality groups—pathozoospermia (n = 95) and normospermia (n = 62). Additionally, our WES study group was negative for complete AZF microdeletions of the Y-chromosome. The normospermia group included men with normal sperm parameters in accordance with the WHO-recommended reference limit. The pathozoospermia group included men with impaired semen quality, namely, with any combined parameters of sperm concentration <15 × 10⁶/ml, and/or progressive motility <32%, and/or normal morphology <4%. The WES was performed for all 157 samples. Subsequent calling and filtering of variants were carried out according to the GATK Best Practices recommendations. On the genotyping stage, the samples were combined into four cohorts: three sets corresponded to three ethnic groups, and the fourth set contained all the 157 whole-exome samples. Association of the obtained polymorphisms with semen quality parameters was investigated using the χ2 test. To prioritize the obtained variants associated with pathozoospermia, their effects were determined using Ensembl Variant Effect Predictor. Moreover, polymorphisms located in genes expressed in the testis were revealed based on the genomic annotation. As a result, the nine potential SNP markers rs6971091, rs557806, rs610308, rs556052, rs1289658, rs278981, rs1129172, rs12268007, and rs17228441 were selected for subsequent verification on our previously collected population sample (about 1,500 males). The selected variants located in seven genes FAM71F1, PPP1R15A, TRIM45, PRAME, RBM47, WDFY4, and FSIP2 that are expressed in the testis and play an important role in cell proliferation, meiosis, and apoptosis.

Heat stress response of somatic cells in the testis

The testis is a temperature-sensitive organ that needs to be maintained 2-7 °C below core body temperature to ensure the production of normal sperm. Failure to maintain testicular temperature in mammals impairs spermatogenesis and leads to low sperm counts, poor sperm motility and abnormal sperm morphology in the ejaculate. This review discusses the recent knowledge on the response of testicular somatic cells to heat stress and, specifically, regarding the relevant contributions of heat, germ cell depletion and inflammatory reactions on the functions of Sertoli and Leydig cells. It also outlines mechanisms of testicular thermoregulation, as well as the thermogenic factors that impact testicular function.

Regional and ethnic differences in semen quality and reproductive hormones in Russia: A Siberian population-based cohort study of young men

Background

This is the first large‐scale Russian study describing semen quality and reproductive hormone levels among young men.

Objectives

The aim of the study was to compare semen quality and reproductive hormone levels in young men of four cities and three ethnic groups living in the Siberian region of Russia and to find out ethnic or environmental reasons for regional differences.

Materials and methods

The study population consisted of 1291 young men from Novosibirsk, Kemerovo, Ulan‐Ude, and Yakutsk, including 1013 men of three most numerous ethnic groups: Slavs, Buryats, and Yakuts. Each participant provided one sperm and blood sample, information about lifestyle and ethnicity. Anthropometric parameters, semen quality and reproductive hormone levels, were evaluated.

Results

Significant regional and ethnic differences were detected for semen and reproductive hormone parameters. Median sperm concentrations in Novosibirsk, Kemerovo, Ulan‐Ude, and Yakutsk were 54.6, 39.9, 34.7, 33.1 × 10⁶/ml; total sperm counts—202.5, 138.7, 97.9, 93.4 × 10⁶; percentages of morphologically normal spermatozoa—7.8%, 6.5%, 6.3%, 5.0%, respectively. Median sperm concentrations in Slavs, Buryats, and Yakuts were 43.7, 37.0, 30.6 × 10⁶/ml; total sperm counts—150.0, 102.3 and 74.8 × 10⁶; percentages of morphologically normal spermatozoa—6.8%, 6.8%, 4.8%, respectively.

Discussion

The young men in Novosibirsk and Kemerovo, populated by Slavs, had a higher semen quality compared to Ulan‐Ude and Yakutsk, populated by Buryats and Yakuts, apparently due to the higher testicular function in Slavic compared to Asian ethnicity. Impaired spermatogenesis in young men in Kemerovo compared to Novosibirsk, located in the same climatic zone and having a socio‐cultural and ethnic identity, may be due to the influence of a polluted environment.

Conclusion

The findings suggest that ethnic composition and environment may be responsible for regional differences in semen and reproductive hormone parameters.

Distribution of semen examination results 2020 - A follow up of data collated for the WHO semen analysis manual 2010

BACKGROUND

It is now 11 years since publication of the WHO 2010 guidelines for semen assessment values, and it is critical to determine whether they are still valid and/or whether they should be modified.

OBJECTIVES

To utilise data published since 2010 and combine these with data used in the 2010 assessment to provide an updated and more comprehensive representation of the fertile man. This may be utilised to present an updated distribution of values for use by WHO in 2021.

MATERIALS AND METHODS

Two specific analyses were performed namely, (1) Analysis 1: Examination of published data following publication of WHO 2010 [termed 2010-2020 data]. (2) Analysis 2: Examination of the data used to help formulate the 2010 distribution of values combined with the data from Analysis (1) [termed WHO 2020].

RESULTS

In total, data from more than 3500 subjects, from twelve countries and five continents were analysed. The 5^th centile values for concentration, motility and morphology are: 16 × 10⁶ /ml, 30% progressive motility [42% total motility] and 4% normal forms.

DISCUSSION

This study presents substantial additional information to establish more comprehensive and globally applicable lower reference values for semen parameters for fertile men although they do not represent distinct limits between fertile and subfertile men. There are still data missing from many countries and, some geographical regions are not represented. Moreover, the number of subjects although significant is still relatively low (<4000).

CONCLUSION

These distributions of values now include semen analysis providing a more global representation of the fertile man. Increasing the number of subjects provides robust information that is also more geographically representative.

[AFU and SALF recommendations for the evaluation of male infertility]

BACKGROUND

The aim of these Association Française d'Urologie (AFU) and Société d'Andrologie de Langue Française (SALF) common recommendations are to provide practice guidelines for the French Urological and Andrological community regarding the evaluation of infertile men.

MATERIAL AND METHODS

Literature search in PubMed using the keywords "male infertility", "diagnosis", "management" and "evaluation" limited to clinical articles in English and French prior to 1/01/2020. To inform the level of evidence, the HAS grading system (2013) was applied.

RESULTS

Concerning the evaluation of infertile men, the AFU and the SALF recommend : (1) a systematic interview exploring the family history, the fertility history of the man outside the couple, the patient's personal history that may have an impact on his fertility, lifestyle habits, treatments, symptoms and possible sexual difficulties of the couple; (2) a general physical examination to assess signs of hypogonadism and secondary sexual characters; (3) a scrotal physical examination performed by an urologist or andrologist to assess (i) the testes for volume and consistency, (ii) vas deferens and epididymes for total or partial absence or nodules, and (iii) presence of varicoceles; (4) Performing two semen analyses, according to World Health Organization guidelines, if the first one has at least one abnormaly; (5) a scrotal ultrasound as part of routine investigation, that can be completed with an endorectal pelvic ultrasound according to the clinic; (6) an endocrine evaluation with at least a Testosterone and FSH serum determination; (7) Karyotype analysis in infertile men with a sperm concentration ≤10 10⁶/mL; (8) assessment of Yq microdeletions in infertile men with a sperm concentration ≤1 10⁶/mL; (9) Cystic fibrosis transmembrane conductance regulator gene evaluation in case of suspicion for bilateral or unilateral congenital agenesis of vas deferens and seminal vesicles. The interest of tests analyzing DNA fragmentation (TUNEL, SCSA) is still under investigation.

CONCLUSION

These guidelines can be applied in routine clinical practice in all infertile men.

Semen quality and waiting time to pregnancy explored using association mining

BACKGROUND

Assessment of semen quality is a key pillar in the evaluation of men from infertile couples. Usually, semen parameters are interpreted individually because the interactions between parameters are difficult to account for.

OBJECTIVES

To determine how combinations of classical semen parameters and female partner age were associated with waiting time to pregnancy (TTP).

MATERIALS AND METHODS

Semen results of 500 fertile men, information of TTP, and partner age were used for regressions and to detect breaking points. For a modified Association Rule Mining algorithm, semen parameters were categorized as High, Medium, and Low.

RESULTS

Men ≤32.1 years and women ≤32.9 years had shorter TTP than older. Decreasing TTP was associated with increasing level of individual semen parameters up to threshold values: sperm concentration 46 mill/mL, total sperm count 179 mill, progressive motility 63%, and normal morphology 11.5%. Using association mining, approximately 100 combinations of semen parameters and partner age were associated with TTP. TTP ≤ 1 month often co-occurred with high percentages of progressive motility (≥62%) and morphologically normal spermatozoa (≥10.5%). Furthermore, TTP ≤ 1 did not tend to appear with lower percentages of these two semen parameters or high partner age (≥32 years). However, high percentages of motile or normal spermatozoa could not compensate for sperm concentration ≤42 mill/mL or total sperm count ≤158 mill. The prolonging effect of high partner age could not be compensated for by the man's semen quality.

DISCUSSION AND CONCLUSION

Using association mining, we observed that TTP was best predicted when combinations of semen parameters were accounted for. Sperm counts, motility, and morphology were all important, and no single semen parameter was inferior. Additionally, female age above 32 years had a negative impact on TTP that could not be compensated for by high semen parameters of the man.

Impaired spermatogenesis in COVID-19 patients

BACKGROUND

The current study aimed to determine the impact of SARS-CoV-2 infection on male fertility.

METHODS

This is a single-center, hospital-based observational study that included autopsied testicular and epididymal specimens of deceased COVID-19 male patients (n=6) and recruited recovering COVID-19 inpatients (n=23) with an equal number of age-matched controls, respectively. We performed histopathological examinations on testicular and epididymal specimens, and also performed TUNEL assay and immunohistochemistry. Whereas, we investigated the semen specimen for sperm parameters and immune factors.

FINDINGS

Autopsied testicular and epididymal specimens of COVID-19 showed the presence of interstitial edema, congestion, red blood cell exudation in testes, and epididymides. Thinning of seminiferous tubules was observed. The number of apoptotic cells within seminiferous tubules was significantly higher in COVID-19 compared to control cases. It also showed an increased concentration of CD3+ and CD68+ in the interstitial cells of testicular tissue and the presence of IgG within seminiferous tubules. Semen from COVID-19 inpatients showed that 39.1% (n=9) of them have oligozoospermia, and 60.9% (n=14) showed a significant increase in leucocytes in semen. Decreased sperm concentration, and increased seminal levels of IL-6, TNF-α, and MCP-1 compared to control males were observed.

INTERPRETATION

Impairment of spermatogenesis was observed in COVID-19 patients, which could be partially explained as a result of an elevated immune response in testis. Additionally, autoimmune orchitis occurred in some COVID-19 patients. Further research on the reversibility of impairment and developing treatment are warranted.

FUNDING

This study was supported by Ministry of Science and Technology of China Plan, Hubei Science and Technology Plan, National Key Research and Development Program of China, HUST COVID-19 Rapid Response Call, China and National Natural Science Foundation of China; these funding bodies are public institutions, and they had no role in study conception, design, interpretation of results, and manuscript preparation.

Use of Personal Care Products and Semen Quality: A Cross-Sectional Study in Young Danish Men

Personal care products (PCPs) may contain multiple chemicals capable of harming male reproductive function. The aim of this study was, therefore, to assess aggregated PCP exposure and potential associations with measures of semen quality in young men. Participants (n = 1058, age 18–21) were sampled among young men from the Danish National Birth Cohort (DNBC). Upon recruitment in 2017–2019, each man answered an online questionnaire and provided a semen sample. Exposure to 12 common types of PCPs was derived from the questionnaire, and the extent of use and co-use was analyzed. We applied a negative binomial regression model to estimate percentage differences in semen parameters between low, medium and high PCP exposure groups. All participants were exposed to at least one PCP more than once a week, resulting in a mean number (SD) of 5.3 (2.0) PCPs currently used. Most participants (92%) were also exposed to fragranced products on a weekly basis. Little association was observed between aggregated exposure to PCPs and sperm concentration, total sperm count, semen volume, sperm motility and morphology. Despite prevalent use of multiple PCPs, we found little indication of adverse effects of aggregated overall or fragranced PCP exposure on semen quality.

High serum FSH is not a risk factor for low bone mineral density in infertile men

BACKGROUND

Male infertility is associated with a higher long-term morbidity and mortality risk. However, it is not clear which diseases are contributing to this risk. Osteoporosis is a possible factor, as it is a frequent disease and sex steroids regulate both fertility and bone health. Furthermore, there are data indicating that high FSH levels in women are related to low bone mineral density (BMD), independent of estradiol levels. As infertile men often have increased FSH, already from a young age, this could be a risk factor for impaired bone health in later life.

METHODS

One hundred and thirty-seven men with a history of male factor infertility due to spermatogenic failure (SgF men) as well as a control group of 70 men from couples treated with IVF for female factor infertility (non-SgF men) were included in a long-term follow-up study. Men with explained infertility, including testosterone deficiency, were not included. Data from baseline fertility investigations were retrieved from the patient files of the SgF men. At follow-up hormonal and semen analysis were performed and axial, femoral and total body BMD was measured by dual X-ray absorptiometry in all men. Multiple linear regression was used to assess differences between SgF and non-SgF men and to study associations between FSH levels and BMD.

RESULTS

Median follow-up time was 14.8 years (5th-95th percentile 11.3-18.2) after fertility assessment for SgF men and 15.6 years (12.1-18.5) for non-SgF men (p = 0.033). When comparing the two groups, no significant differences in total T, free T or E2 levels were apparent at follow-up. As expected, LH and FSH were higher in SgF men ((median (5th-95th percentile)) for LH (IU/L): 4.3 (2.2-13.6) for SgF men and 3.0 (1.4-5.8) for non-SgF men (p < 0.001); FSH (IU/L): 9.8 (2.8-35.5) versus 3.7 (1.6-8.7); p < 0.001), and inhibin B and semen parameters were lower in SgF men. There were no differences in BMD between the two groups at follow-up. Furthermore, both groups had median Z-scores close to zero at all sites, indicating that BMD is not different when compared to age-matched healthy men. In SgF men, neither baseline FSH, nor FSH at follow-up, was associated with BMD at the different sites at follow-up.

CONCLUSION

Men with spermatogenic failure are not at increased risk for impaired bone health when middle aged. Furthermore, infertile men with high FSH levels do not have lower BMD.

Heat SHOCK proteins in equine spermatozoa: Expression and correlation to kinetic and environmental parameters

Heat Shock Proteins are chaperones primary involved in the repair of cellular damages induced by temperature. The harmful effect of temperature on the male gonad is well known, on the contrary knowledge on the effects of the environment on semen quality are still insufficient. The aim of this paper was to learn more about the role of HSPs and the environment in modulating the physiology of equine male gonads. We showed a detailed analysis of equine semen characteristic and the expression level of three HSPs (60-70-90) over a one-year period analyzing the effects of temperature and humidity and the correlation among the different variables. We showed also that the interpretation of results depends strongly on the way in which data are assembled and analyzed, therefore we compared results obtained from three different ways of grouping: according to single months, to weather seasons and to mare reproductive periods. Results showed that the expression of the three HSPs is correlated to the environment through temperature and humidity and that it reaches the highest level in the breeding season and in summer. We found also that HSPs expression is correlated to some variables describing the quality of equine semen (concentration) and the kinetic of spermatozoa (total motility-MOT, %, average path velocity -VAP, μm/s- and lateral head displacement -ALH, μm). No correlation was found between HSPs expression and the mitochondrial membrane potential; while viability and HSP90 expression resulted positively correlated. The month-by-month analysis evidenced that in February equine semen has the highest kinetic characteristics (increased linearity -LIN, %-, straightness -STR, % -and average path velocity -VAP, μm/s) with the highest number of motile, progressive motile and rapid cells. These results may have a great impact in the comprehension of functional aspects of the physiology of equine semen and may have potential implications for breeders who want to understand the period (and/or month) of the year in which equine semen reaches the best characteristics with increased chances for better results in reproductive practice.

Cryopreservation of single-sperm: where are we today?

BACKGROUND

Patients with severe oligospermia and nonobstructive azoospermia have very limited numbers of viable sperm in their epididymal and testicular samples. Thus, cryopreservation of their sperm is performed to avoid repeated sperm retrievals and to preserve their sperm from any side effects of any treatment regimens.

MAIN BODY

The development of intracytoplasmic sperm injection technology has extended the therapeutic capacity of assisted reproductive technology for men with azoospermia via the surgical or percutaneous isolation of sperm from the testis/epididymis. The conventional cryopreservation techniques are inadequate for preserving individually selected sperm. The technique for freezing single sperm was first developed in 1997 and has been explored from the perspective of frozen carriers, freezing programs, and cryoprotectant formulations. Among these methods, advances in frozen carriers have directly improved single-sperm freezing technology. In this review, we evaluate the different technologies for the cryopreservation of single sperm by discussing the advantages and disadvantages of different freezing methods, their clinical applications, and the outcomes for a range of frozen carriers.

CONCLUSION

Our review article describes the latest and current technologies implemented for the cryopreservation of single sperm that could potentially benefit patients with severe oligospermia and who rarely have any sperm in their ejaculate. This review provides a platform to understand the process and pitfalls of single-sperm cryopreservation to ensure further improvements in the cryopreservation technology in future studies.

Do lifestyle practices impede male fertility?

Alongside an increasing prevalence of couple and male infertility, evidence suggests there is a global declining trend in male fertility parameters over the past few decades. This may, at least in part, be explained through detrimental lifestyle practices and exposures. These include alcohol and tobacco consumption, use of recreational drugs (e.g., cannabis, opioids and anabolic steroids), poor nutritional habits, obesity and metabolic syndrome, genital heat stress (e.g., radiation exposure through cell phones and laptops, prolonged periods of sitting, tight-fitting underwear and recurrent hot baths or saunas), exposure to endocrine-disrupting chemicals (e.g., pesticide residue, bisphenol A, phthalates and dioxins) and psychological stress. This review discusses these lifestyle practices and the current evidence associated with male infertility. Furthermore, known mechanisms of action are also discussed for each of these. Common mechanisms associated with a reduction in spermatogenesis and/or steroidogenesis due to unfavourable lifestyle practices include inflammation and oxidative stress locally or systemically. It is recommended that relevant lifestyle practices are investigated in clinical history of male infertility cases, particularly in unexplained or idiopathic male infertility. Appropriate modification of detrimental lifestyle practices is further suggested and recommended in the management of male infertility.

The Uruguayan semen donor population: A twenty-eight-year retrospective study

Several studies have reported a global decline in seminal quality over the years. The objective of this study was to describe the semen donor population of Uruguay through comparing data of successive samples banked by the same donors and the analysis of their semen and physical characteristics, ancestry origin and educational level. A total of 3,449 ejaculated samples collected from 71 donors, cryobanked between 1989 and March 2017 at Fertilab, were analysed. Results revealed a mean age of 23.90 ± 3.98 years, an average weight of 74.95 ± 1.09 kg and a mean height of 1.78 ± 0.06 m. The majority of the donors trace their origin to Europe (74.65%, 53/71) and 66.19% (47/71) have a level of education higher than secondary school. We observed longitudinal differences in two parameters, that is sperm concentration and semen volume. Sperm concentration declined, while semen volume increased significantly over the 28-year period. The results of the present study are in accordance with that of previous articles that also reported a decline in sperm concentration over time. However, no differences were observed in total sperm number per ejaculate due to the increase in semen volume values, thus reflecting no real changes in sperm production over time.

Semen quality pattern and age threshold: a retrospective cross-sectional study of 71,623 infertile men in China, between 2011 and 2017

BACKGROUND

The aim of this study was to provide information on the semen quality pattern of infertile men and age thresholds for semen parameters in China.

METHODS

This was a retrospective cross-sectional study investigating 71,623 infertile men from the Reproductive and Genetic Hospital of CITIC Xiangya in Hunan, China, from 2011 to 2017. The Kruskal-Wallis test, Mann-Kendall test, linear regression model and joinpoint regression were used.

RESULTS

Although erratic changes were observed in the median semen parameters (sperm concentration 40.1-52.1 × 10⁶/ml, total sperm count 117.8-153.1 × 10⁶, sperm progressive motility 33.4-38.1%) during the 7 years of observation, no significant decrease in semen quality was found, and 47.88% of infertile men showed normal semen parameters according to the World Health Organization (WHO) criteria. According to the joinpoint regression analysis, sperm progressive motility appeared to decrease earlier than the sperm concentration and total sperm count (at 28, 58, and 42 years of age, respectively).

CONCLUSIONS

There is no evidence of a deterioration in semen quality among infertile men in Hunan, China. Semen parameters decreased with increasing age, with turning points noted at different ages. Semen parameters are not absolute evidence for the assessment of male fertility potential. Therefore, we believe that, among semen parameters, the sperm concentration is the best predictor of fertility for ART, followed by motility. Decreased sperm motility may affect natural pregnancy, but it is not necessary for successful IVF.

The current status and future of andrology: A consensus report from the Cairo workshop group

BACKGROUND

In attempting to formulate potential WHO guidelines for the diagnosis of male infertility, the Evidence Synthesis Group noted a paucity of high-quality data on which to base key recommendations. As a result, a number of authors suggested that key areas of research/evidence gaps should be identified, so that appropriate funding and policy actions could be undertaken to help address key questions.

OBJECTIVES

The overall objective of this Consensus workshop was to clarify current knowledge and deficits in clinical laboratory andrology, so that clear paths for future development could be navigated.

MATERIALS AND METHODS

Following a detailed literature review, each author, prior to the face-to-face meeting, prepared a summary of their topic and submitted a PowerPoint presentation. The topics covered were (a) Diagnostic testing in male fertility and infertility, (b) Male fertility/infertility in the modern world, (c) Clinical management of male infertility, and (d) The overuse of ICSI. At the meeting in Cairo on February 18, 2019, the evidence was presented and discussed and a series of consensus points agreed.

RESULTS

The paper presents a background and summary of the evidence relating to these four topics and addresses key points of significance. Following discussion of the evidence, a total of 36 consensus points were agreed.

DISCUSSION

The Discussion section presents areas where there was further debate and key areas that were highlighted during the day.

CONCLUSION

The consensus points provide clear statements of evidence gaps and/or potential future research areas/topics. Appropriate funding streams addressing these can be prioritized and consequently, in the short and medium term, answers provided. By using this strategic approach, andrology can make the rapid progress necessary to address key scientific, clinical, and societal challenges that face our discipline now and in the near future.

Semen quality of young men in Switzerland: a nationwide cross-sectional population-based study

BACKGROUND

Sperm counts have been steadily decreasing over the past five decades with regional differences in the Western world. The reasons behind these trends are complex, but numerous insights indicate that environmental and lifestyle factors are important players.

OBJECTIVE

To evaluate semen quality and male reproductive health in Switzerland.

MATERIALS AND METHODS

A nationwide cross-sectional study was conducted on 2523 young men coming from all regions of Switzerland, recruited during military conscription. Semen volume, sperm concentration, motility, and morphology were analyzed. Anatomy of the genital area and testicular volume was recorded. Testicular cancer incidence rates in the general population were retrieved from Swiss regional registries.

RESULTS

Median sperm concentration adjusted for period of sexual abstinence was 48 million/mL. Comparing with the 5th percentile of the WHO reference values for fertile men, 17% of men had sperm concentration below 15 million/mL, 25% had less than 40% motile spermatozoa, and 43% had less than 4% normal forms. Disparities in semen quality among geographic regions, urbanization rates, and linguistic areas were limited. A larger proportion of men with poor semen quality had been exposed in utero to maternal smoking. Furthermore, testicular cancer incidence rates in the Swiss general population increased significantly between 1980 and 2014.

DISCUSSION

For the first time, a systematic sampling among young men has confirmed that semen quality is affected on a national level. The median sperm concentration measured is among the lowest observed in Europe. No specific geographical differences could be identified. Further studies are needed to determine to what extent the fertility of Swiss men is compromised and to evaluate the impact of environmental and lifestyle factors.

CONCLUSION

A significant proportion of Swiss young men display suboptimal semen quality with only 38% having sperm concentration, motility, and morphology values that met WHO semen reference criteria.

Non Concurrent Multimodal Stress Decreases Sperm Quality and Motor Activity in Male Wister Albino Rats

Every human being is exposed to the stress in one or the other form in the day to day life. Most of the existing studies on the impact of stress on the male reproduction were assessed by using single stressor, which may lead habituation to that stressor. The present study intends to estimate the consequence of stress on motor activity, sperm quality and histopathology of the testis in stress-induced male rats using multimodal stress one per day. Four weeks old Wister albino rats were randomly split into 4 groups and induced multimodal stress at different ages of life span. After induction of stress serum corticosterone levels, muscle strength and coordination, quality of sperm and histopathology of testes were estimated. Elevated serum corticosterone levels and body weight, reduced muscle strength, coordination. Sperm concentration and motility was significantly reduced and increased morphologically abnormal sperm in stress induced animals but sperm viability was not altered much. Histopathology of testes in stress received animals showed decreased tubular diameter and increased intertubular space. Multimodal stress caused elevated serum corticosterone and body weight, decreased motor activity, sperm quality and degenerative changes in the testis

Male Infertility Problem: A Contemporary Review on Present Status and Future Perspective

Semen quality plays a pivotal role in maintaining healthy fertilizing ability of spermatozoa. Male infertility is a rising global problem with an increasing declining in male semen quality among men living in Africa, Europe, North American, and Asia. Though the sperm acquire proactive mechanisms during spermatogenesis and their epididymal maturation, they still remain viable for toxic insult. Declining semen quality is a major contributor to infertility. Studies have postulated that different factors, such as exposure to pesticides, industrial chemicals, heavy metals, obesity, alcoholism, tobacco smoking, sedentary lifestyles, poor nutrient intake, oxidative stress, physiological factors, genetic factors can influence male fertility. Routine semen analysis and assays for sperm chromatin integrity are the most widely utilized and best studied adjunctive diagnostics in male infertility. Over the years, scientists have developed different treatment options for male infertility. Male infertility with known etiology can be treated successfully, but other causes like genetic factors require pragmatic approaches. This article summarizes protective mechanisms of spermatogenesis, causes, diagnosis, and both modern and traditional treatment approaches of male infertility. Further, this article highlights present issues and direction for future exploration of the male infertility problem.

Heat exposure induces oxidative stress and DNA damage in the male germ line

The reproductive consequences of global warming are not currently understood. In order to address this issue, we have examined the reproductive consequences of exposing male mice to a mild heat stress. For this purpose, adult male mice were exposed to an elevated ambient temperature of 35°C under two exposure models. The first involved acute exposure for 24 h, followed by recovery periods between 1 day and 6 weeks. The alternative heating regimen involved a daily exposure of 8 h for periods of 1 or 2 weeks. In our acute model, we identified elevated sperm mitochondrial ROS generation (P < 0.05), increased sperm membrane fluidity (P < 0.05), DNA damage in the form of single-strand breaks (P < 0.001), and oxidative DNA damage (P < 0.05), characteristic of an oxidative stress cascade. This DNA damage was detected in pachytene spermatocytes (P < 0.001) and round spermatids (P < 0.001) isolated from testes after 1 day heat recovery. Despite these lesions, the spermatozoa of heat-treated mice exhibited no differences in their ability to achieve hallmarks of capacitation or to fertilize the oocyte and support development of embryos to the blastocyst stage (all P > 0.05). Collectively, our acute heat stress model supports the existence of heat susceptible stages of germ cell development, with the round spermatids being most perturbed and spermatogonial stem cells exhibiting resistance to this insult. Such findings were complemented by our chronic heat stress model, which further supported the vulnerability of the round spermatid population.

How 1 h of abstinence improves sperm quality and increases embryo euploidy rate after PGT-A: a study on 106 sibling biopsied blastocysts

PURPOSE

The aim of our study was to evaluate the influence of different ejaculatory abstinence time frames (several days versus 1 h) on semen parameters, blastocysts ploidy rate, and clinical results in assisted reproduction cycles on sibling oocytes.

METHODS

This is a prospective study including 22 preimplantation genetic testing for aneuploidy (PGT-A) cycles performed between November 2015 and December 2018. Male partners with oligoastenoteratozoospermia produced two semen samples on the day of oocyte retrieval: the first one after several days of abstinence and the second, 1 h after the first one. Oocytes from each patient were divided into two groups: those in group 1 were injected with spermatozoa from the first ejaculate (N = 121) and oocytes in group 2 with spermatozoa from the second one (N = 144). Outcomes of aniline blue test, fertilization, blastocyst formation, ploidy rates, and clinical results were compared between the two groups.

RESULTS

Semen volume resulted lower in the second sperm retrieval. Sperm concentration, motility, and morphology were similar in the two groups. A total of 106 blasotcysts were biospied. Higher blastocyst euploidy rates resulted in group 2 (43.6%) than in group 1 (27.5%). A higher percentage of mature chromatine was observed in group 2.

CONCLUSION

Using spermatozoa from samples with a shorter abstinence could be a simple method to select higher quality spermatozoa, reducing aneuploidy rate in blastocysts. Prospective randomized controlled trials should be performed to confirm the potential advantage of using semen samples with short abstinence period to improve the outcome of assisted reproduction cycles.

Decrease in semen quality and Leydig cell function in infertile men: a longitudinal study

STUDY QUESTION

Are infertile men with reduced semen quality at risk of a further decrease in testicular function?

SUMMARY ANSWER

Infertile men with severely reduced semen quality risk further deterioration of semen quality 15 years after treatment for infertility, and a lower baseline sperm concentration was associated with a more pronounced increase in LH and decrease in testosterone/LH ratio at follow-up.

WHAT IS KNOWN ALREADY

Male factors account for up to 50% of human infertility. The most common finding is spermatogenic failure (SgF) yet the life course of semen quality and testosterone production in such men has not been described.

STUDY DESIGN, SIZE, DURATION

A follow-up study of men with SgF was performed 15 years after the initial infertility assessment between January 1995 and December 2000.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Hospital records were used to identify potential participants in the study. A total of 137 men with primary male infertility due to SgF and 70 controls with good semen quality from couples with female factor infertility who attended a tertiary referral centre were included: the participation rate was 31% and 26%, respectively. The men provided semen samples and underwent a physical examination. Blood samples were taken to measure levels of reproductive hormones (FSH, LH, testosterone, sex hormone-binding globulin, estradiol and inhibin B). Current results were compared with results from the initial assessments.

MAIN RESULTS AND THE ROLE OF CHANCE

At the time of follow up the SgF men had significantly lower Leydig cell capacity than the control group as well as much lower semen quality. For the SgF men, between baseline sampling and follow up, the median sperm concentration decreased from 1.9 to 0.6 mill/ml and total sperm count from 7.7 to 2.0 million (P = 0.019 and 0.012, respectively), and 10% developed azoospermia. Calculated free testosterone (cFT), but not total testosterone (tT) decreased in the SgF group by ~0.6% (95% CI 0.1-1.2%) per year. In the SgF group, LH increased by 1.6% (CI 0.9-2.3%) annually, and consequently tT/LH and cFT/LH ratios had decreased by 1.3% (CI 0.5-2.1) and 2.1% (CI 1.2-3.0%), respectively. The increase in LH and the decreases in tT/LH and cFT/LH ratios were more pronounced in men with lower baseline sperm concentrations.

LIMITATIONS, REASONS FOR CAUTION

We consider the case group as representative of infertile men not in need of testosterone treatment at baseline investigation, but do not have information on those that chose not to participate in the follow-up study. There were alterations in some hormone analysis methods during the follow-up period that may introduce uncertainty in interpretation of long-term changes in hormone levels despite rigorous quality control. The validity of the control group suffers from a lack of hormone values at baseline. Also, at follow-up, for practical reasons only one semen sample could be obtained, which makes the effect estimate more uncertain and there is a risk of non-differential misclassification.

WIDER IMPLICATIONS OF THE FINDINGS

Without being able to predict individual outcomes, it is prudent to consider sperm cryopreservation or advise not to postpone fertility treatment when men present with infertility due to impaired semen quality. Whether partly compensated Leydig cell insufficiency in men with SgF will eventually develop into overt testosterone deficiency cannot be determined from our study.

STUDY FUNDING/COMPETING INTEREST(s)

Aase and Einar Danielsen (Grant no. 10-001053), Nordic Research Committee (Grant no. 5109), The Kirsten and Freddie Johansen Fund, and Rigshospitalet's Research Fund (grant no. R24-A812). There are no competing interests.

The impact of sociodemographic characteristics, lifestyle, work exposure and medical history on semen parameters in young Chinese men: A cross-sectional study

There is an ongoing debate on the declining semen quality, and unfortunately, existing evidence is inconclusive and inconsistence. We evaluated the impact of sociodemographic characteristics, lifestyle, medical history and work exposure on semen quality. Univariate and multivariate analysis was used to investigate the association between different risk factors and semen quality parameters. Total sperm count (p = 0.041), sperm concentration (p = 0.007), normal morphology (p = 0.002), total motility (p = 0.004) and progressive motility (p = 0.009) decreased in men with varicocele. Sperm concentration increased in tea (p = 0.044); progressive and total motility increased in cola (p = 0.018, p = 0.012) consumers. Progressive and total motility decreased in urogenital surgery (p = 0.016, p = 0.014) and infection (p = 0.037, p = 0.022). However, age, coffee and alcohol drinking, physical activities, sleep duration and cell phone use were unrelated to any of semen parameters. Interestingly, semen volume (p < 0.0001), total sperm count (p < 0.0001) and concentration (p < 0.033) increased with longer abstinence period (>5 days); normal morphology (p = 0.013) improved in men with higher body mass index (BMI > 24), curvilinear velocity (p = 0.042) increased with smoking; semen volume (p = 0.050) increased in manual labourers. This study highlights the importance of sociodemographic characteristics, lifestyle, occupational exposure and medical history and provides time trends in semen quality, its clinical importance and direction for further research.

Average sperm count remains unchanged despite reduction in maternal smoking: results from a large cross-sectional study with annual investigations over 21 years

STUDY QUESTION

How are temporal trends in lifestyle factors, including exposure to maternal smoking in utero, associated to semen quality in young men from the general population?

SUMMARY ANSWER

Exposure to maternal smoking was associated with lower sperm counts but no overall increase in sperm counts was observed during the study period despite a decrease in this exposure.

WHAT IS KNOWN ALREADY

Meta-analyses suggest a continuous decline in semen quality but few studies have investigated temporal trends in unselected populations recruited and analysed with the same protocol over a long period and none have studied simultaneous trends in lifestyle factors.

STUDY DESIGN, SIZE, DURATION

Cross-sectional population-based study including ~300 participants per year (total number = 6386) between 1996 and 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study is based on men from the Greater Copenhagen area, Denmark, with a median age of 19 years, and unselected with regard to fertility status and semen quality. The men delivered a semen sample, had a blood sample drawn and a physical examination performed and answered a comprehensive questionnaire, including information on lifestyle and the mother's pregnancy. Temporal trends in semen quality and lifestyle were illustrated graphically, and trends in semen parameters and the impact of prenatal and current lifestyle factors were explored in multiple regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Throughout the study period, 35% of the men had low semen quality. Overall, there were no persistent temporal trends in semen quality, testicular volume or levels of follicle-stimulating hormone over the 21 years studied. The men's alcohol intake was lowest between 2011 and 2016, whereas BMI, use of medication and smoking showed no clear temporal trends. Parental age increased, and exposure in utero to maternal smoking declined from 40% among men investigated in 1996-2000 to 18% among men investigated in 2011-2016. Exposure to maternal smoking was associated with lower sperm counts but no overall increase in sperm counts was observed despite the decrease in this exposure.

LIMITATIONS, REASONS FOR CAUTION

Information of current and prenatal lifestyle was obtained by self-report, and the men delivered only one semen sample each.

WIDER IMPLICATIONS OF THE FINDINGS

The significant decline in in utero exposure to maternal smoking, which was not reflected in an overall improvement of semen quality at the population level, suggest that other unknown adverse factors may maintain the low semen quality among Danish men.

STUDY FUNDING/COMPETING INTEREST(S)

The study has received financial support from the ReproUnion; the Research fund of Rigshospitalet, Copenhagen University Hospital; the European Union (Contract numbers BMH4-CT96-0314,QLK4-CT-1999-01422, QLK4-CT-2002-00603, FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers foundation; and Svend Andersens Foundation. None of the funders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions.

TRIAL REGISTRATION NUMBER

N/A.

Declining Sperm Counts… or Rather Not? A Mini Review

Importance

Temporal global trends of sperm quality remain a matter of debate.

Objective

The aim of this study was to present a comprehensive review of studies reporting on sperm quality counts, summarize the main end points, and assess the main reasons for potential discrepancies.

Evidence Acquisition

An evidence-based review of PubMed and Scopus databases was performed regarding studies reporting on modification of sperm quality counts, independently of study character, study language, or date.

Results

Since the meta-analysis of Carlsen et al in 1992 (Br Med J 1992;305:609-613) that suggested an annual decline in sperm count of 1%, several reports confirmed the decline in sperm quality, whereas others disproved them, suggesting a slight increase or absence of change in sperm count. Such controversies may be attributed to geographical and time-related variability in sperm values and also to several confounding factors that influence the semen parameters. Intrinsic weaknesses of the studies include heterogeneity of subjects recruited, lack of adjustment for confounding factors, and samples that do not always represent the general population.

Conclusions

No consensus exists on whether sperm counts actually decrease because studies' results are often controversial or inconclusive with methodological deficiencies. More prospective, large-scale, population based studies are needed in order to provide sound evidence of possible global trends in sperm count.

Inconsistent Adoption of World Health Organization V (2010) Semen Analysis Reference Ranges in the United States Eight Years After Publication

OBJECTIVE

To determine the percentage of laboratories in the United States that have adopted the World Health Organization 2010 (WHO 5) semen analysis (SA) reference values 6years after their publication.

METHODS

Laboratories were identified via 3 approaches: using the Clinical Laboratory Improvement Amendments (CLIA) website, the CDC's 2015 Assisted Reproductive Technology Fertility Clinical Success Rate Report, and automated web searches. Laboratories were contacted by phone or email to obtain de-identified SA reports and reference ranges.

RESULTS

We contacted 617 laboratories in 46 states, of which 208 (26.7%) laboratories in 45 states were included in our analysis. 132 (63.5%) laboratories used WHO 5 criteria, 57 (27.4%) used WHO 4 criteria, and 19 (9.1%) used other criteria. WHO 5 criteria adoption rates varied by geographic region, ranging from 87.5% (35/40) in the Midwest to 50.0% (33/66) in the West. There was a greater adoption rate of WHO 5 reference values in academic affiliated (23/26, 88.5%) compared to non-academic affiliated laboratories (110/182, 60.4%) (P = .028).

CONCLUSION

While the majority of laboratories have adopted WHO 5 criteria following its release 6years ago, a large percentage (36.5%) use what is now considered outdated criteria. This variability could result in the characterization of a male's semen values as being "within reference range" at one center and "outside of reference range" at another. This inconsistency in classification may result in confusion for the both patient and physician and potentially shift the burden of infertility evaluation and treatment to the female partner.