Evidence of deteriorating semen quality in the United Kingdom: birth cohort study in 577 men in Scotland over 11 years

What is driving the global decline of human fertility? Need for a multidisciplinary approach to the underlying mechanisms

An intense period of human population expansion over the past 250 years is about to cease. Total fertility rates are falling dramatically all over the world such that highly industrialized nations, including China and the tiger economies of SE Asia, will see their populations decline significantly in the coming decades. The socioeconomic, geopolitical and environmental ramifications of this change are considerable and invite a multidisciplinary consideration of the underlying mechanisms. In the short-term, socioeconomic factors, particularly urbanization and delayed childbearing are powerful drivers of reduced fertility. In parallel, lifestyle factors such as obesity and the presence of numerous reproductive toxicants in the environment, including air-borne pollutants, nanoplastics and electromagnetic radiation, are seriously compromising reproductive health. In the longer term, it is hypothesized that the reduction in family size that accompanies the demographic transition will decrease selection pressure on high fertility genes leading to a progressive loss of human fecundity. Paradoxically, the uptake of assisted reproductive technologies at scale, may also contribute to such fecundity loss by encouraging the retention of poor fertility genotypes within the population. Since the decline in fertility rate that accompanies the demographic transition appears to be ubiquitous, the public health implications for our species are potentially devastating.

Combined effects of polystyrene nanoplastics and lipopolysaccharide on testosterone biosynthesis and inflammation in mouse testis

Microplastics (MPs)/nanoplastics (NPs), as a source and vector of pathogenic bacteria, are widely distributed in the natural environments. Here, we investigated the combined effects of polystyrene NPs (PS-NPs) and lipopolysaccharides (LPS) on testicular function in mice for the first time. 24 male mice were randomly assigned into 4 groups, control, PS-NPs, LPS, and PS-NPs + LPS, respectively. Histological alterations of the testes were observed in mice exposed to PS-NPs, LPS or PS-NPs + LPS. Total sperm count, the levels of testosterone in plasma and testes, the expression levels of steroidogenic acute regulatory (StAR) decreased more remarkable in testes of mice treated with PS-NPs and LPS than the treatment with LPS or PS-NPs alone. Compared with PS-NPs treatment, LPS treatment induced more sever inflammatory response in testes of mice. Moreover, PS-NPs combined with LPS treatment increased the expression of these inflammatory factors more significantly than LPS treatment alone. In addition, PS-NPs or LPS treatment induced oxidative stress in testes of mice, but their combined effect is not significantly different from LPS treatment alone. These results suggest that PS-NPs exacerbate LPS-induced testicular dysfunction. Our results provide new evidence for the threats to male reproductive function induced by both NPs and bacterial infection in human health.

The relationship between the intake of dietary fatty acids and minerals with sperm parameters in infertile men

BACKGROUND & AIMS

Infertility has been increasing among Iranian couples. Some epidemiological studies have reported a relationship between infertility and lifestyle patterns, including dietary habits. Our objective was to evaluate the relationship between sperm parameters and the intake of dietary fatty acids and minerals among Iranian infertile men.

METHODS

This cross-sectional was performed on 400 newly diagnosed infertile men at Yazd Reproductive Sciences Institute from July to December 2019. Men whose infertility was confirmed by an andrologist based on the World Health Organization (WHO) criteria were selected. They delivered a semen sample and answered a 168-item semi-quantitative food frequency questionnaire. All data were analyzed using SPSS and STATA software. A p-value of less than 0.5 was considered significant.

RESULTS

In the adjusted model, a significant negative association between sperm motility and the 3rd quartile (Q) of poly-unsaturated fatty acids compared to the 1st quartile) P = 0.02). Also, in the adjusted model, total mobility was significantly increased in the second, third and last quartiles of omega-3 fatty acids compared to the first quartile (P < 0.001, P = 0.02, P < 0.001, respectively). Furthermore, omega-6 fatty acid intake in the last quartile were positively associated with sperm motility (P = 0.01). Moreover, there was a significant association between omega-3 fatty acid intake in the second, third, and last quartiles and sperm normal morphology (P = 0.003, P = 0.018, and P = 0.005, respectively) compared with the first quartile. Further, we observed a significant association between omega-6 fatty acid intake and sperm normal morphology in the last quartile compared with the reference quartile (P = 0.04). Also, the findings showed a significant negative association between the second quartile of sodium and calcium intake and sperm volume compared with the first quartile (P = 0.04, for both) in the adjusted model.

CONCLUSIONS

We concluded that dietary polyunsaturated fatty acid, sodium, and calcium intake are related to sperm morphology, volume, and total motility in Iranian infertile men. However, more research is needed to confirm these relationships and provide evidence to exert these findings into clinical practice.

The Effect of Age on Semen Quality Among Male Partners of Infertile Couples: An Observational Study in a Tertiary Care Center in Eastern India

INTRODUCTION

Male infertility contributes to a significant proportion of infertility cases, and advanced paternal age has been suggested to affect semen quality and fertility. However, the relationship between age and semen quality remains inconclusive, with conflicting findings reported in the literature. This study aimed to investigate the effect of age on semen quality among male partners of infertile couples in a tertiary care center in eastern India.

METHODS

A cross-sectional observational study was conducted, involving 390 male participants aged 21-50 years, who were referred to the andrology laboratory for semen analysis between January 2019 and December 2022. Participants were categorized into three age groups (21-30, 31-40, and 41-50 years). Semen parameters, including sperm concentration, semen volume, motility, and morphology, were assessed according to the World Health Organization guidelines.

RESULTS

Among the participants, no significant differences were observed in semen volume, motility, and morphology across different age groups. However, a statistically significant difference in sperm concentration among the three age groups was observed (p = 0.022). Spearman correlation analysis revealed a positive correlation between age and sperm concentration (r = 0.124, p = 0.013) as well as total sperm count (r = 0.10, p = 0.049).

CONCLUSION

In this study, no significant decline in semen quality with age was found among male partners of infertile couples aged 21-50 years. These findings highlight the complex relationship between age and semen quality and emphasize the need for further research to better understand the underlying mechanisms and provide more conclusive evidence regarding the impact of age on male fertility.

The Price of Human Evolution: Cancer-Testis Antigens, the Decline in Male Fertility and the Increase in Cancer

The increasing frequency of general and particularly male cancer coupled with the reduction in male fertility seen worldwide motivated us to seek a potential evolutionary link between these two phenomena, concerning the reproductive transcriptional modules observed in cancer and the expression of cancer-testis antigens (CTA). The phylostratigraphy analysis of the human genome allowed us to link the early evolutionary origin of cancer via the reproductive life cycles of the unicellulars and early multicellulars, potentially driving soma-germ transition, female meiosis, and the parthenogenesis of polyploid giant cancer cells (PGCCs), with the expansion of the CTA multi-families, very late during their evolution. CTA adaptation was aided by retrovirus domestication in the unstable genomes of mammals, for protecting male fertility in stress conditions, particularly that of humans, as compensation for the energy consumption of a large complex brain which also exploited retrotransposition. We found that the early and late evolutionary branches of human cancer are united by the immunity-proto-placental network, which evolved in the Cambrian and shares stress regulators with the finely-tuned sex determination system. We further propose that social stress and endocrine disruption caused by environmental pollution with organic materials, which alter sex determination in male foetuses and further spermatogenesis in adults, bias the development of PGCC-parthenogenetic cancer by default.

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.

The future of sperm: a biovariability framework for understanding global sperm count trends

The past 50 years have seen heated debate in the reproductive sciences about global trends in human sperm count. In 2017, Levine and colleagues published the largest and most methodologically rigorous meta-regression analysis to date and reported that average total sperm concentration among men from 'Western' countries has decreased by 59.3% since 1973, with no sign of halting. These results reverberated in the scientific community and in public discussions about men and masculinity in the modern world, in part because of scientists' public-facing claims about the societal implications of the decline of male fertility. We find that existing research follows a set of implicit and explicit assumptions about how to measure and interpret sperm counts, which collectively form what we term the Sperm Count Decline hypothesis (SCD). Using the study by Levine and colleagues, we identify weaknesses and inconsistencies in the SCD, and propose an alternative framework to guide research on sperm count trends: the Sperm Count Biovariability hypothesis (SCB). SCB asserts that sperm count varies within a wide range, much of which can be considered non-pathological and species-typical. Knowledge about the relationship between individual and population sperm count and life-historical and ecological factors is critical to interpreting trends in average sperm counts and their relationships to health and fertility.

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.

The effects of Aroclor 1254 alone and in combination with X-rays on the male mice germ cells quantity and quality

The effects of chemical and physical environmental factors are concerned as the main reason of diminished male fertility. The aim of the study was the investigation of the effects of low doses of Aroclor 1254 or combined exposure to low doses of Aroclor 1254 and low doses of ionizing radiation on the sperm quantity and quality of male germ cells including damage to genetic material of adult male mice. Mice were exposed for 2 weeks, 3 times per week by intraperitoneal injection with Aroclor 1254 diluted in corn oil at doses of 1, 2 and 4 mg/kg bw or to whole body X-rays irradiation at doses 0.05 Gy, 0.10 Gy and 0.15 Gy or to combination of X-rays and Aroclor 1254 at following doses 0.05 Gy + 1 mg/kg bw Aroclor 1254, 0.10 Gy + 2 mg/kg bw Aroclor 1254. The samples for sperm count, motility, morphology and DNA integrity of male germ cells estimation were taken from animals just after the end of exposure and 5 weeks later. Irradiation alone deteriorated sperm count and quality. Aroclor 1254 significantly reduced the sperm motility and increased sperm abnormality and at the highest dose also induced DNA damage of gametes. The combined exposure to 0.10 Gy + 2 mg/kg bw of Aroclor 1254 showed the increase in the sperm concentration and the decrease of percentage of abnormal spermatozoa compared to results after irradiation to 0.10 Gy alone. In conclusion, the low doses of Aroclor 1254 used in this study did not significantly reduce the sperm count, but affected the sperm motility, morphology and sometimes also DNA integrity of gametes. In combination with low doses of irradiation, low doses of Aroclor 1254 may ameliorate the harmful effect of irradiation on the male gametes.

Is seminal quality worsening? A 20-year experience in Córdoba, Argentina

PURPOSE

To assess the possible variations in semen quality during the last 20 years in Córdoba, Argentina, and to identify possible causal lifestyle or genitourinary factors.

METHODS

Retrospective study of 23,130 patients attending an andrology laboratory. The 20-year period (2001-2020) was divided into four quinquenniums. Seminal parameters (sperm concentration, motility, morphology, viability, and membrane functional integrity) were classified as normal or abnormal according to WHO, and results were expressed as percentage of patients abnormal for each parameter per quinquennium. In addition, the percentage of patients per quinquennium exposed to the different risk factors (daily alcohol and/or tobacco consumption; occupational exposure to heat or toxics; history of parotitis or varicocele; and high body mass index, BMI) was reported.

RESULTS

Patients included in our study did not show impairment in seminal quality over time. Beyond a transient decrease in normozoospermia in the second and third quinquennium, possibly explained by a parallel increase in teratozoospermia, other important parameters of the spermogram did not change. In fact, abnormalities in sperm concentration (oligozoospermia), total sperm count, viability and response to hypoosmotic test showed a decreasing trend over time. On the other hand, parotitis, varicocele, morbid obesity and regular exposition to heat/toxics were the factors more frequently associated with semen abnormalities; the last two increased their frequency over the study period.

CONCLUSION

The population included in this study did not show a clear impairment in semen quality during the last 20 years. The decreasing patterns found were associated with high BMI and exposure to heat/toxics.

Effects of aging and oviductal hormones on testes, epididymides, and sperm of hamster

Purpose

Aging is a major cause of decreased fertility. Using hamster, we examined the effects of aging on testes, epididymides, and sperm. Additionally, we examined whether progesterone (P4), melatonin (Mel) and 5-hydroxytryptamine (5-HT) mitigated effects of aging on sperm.

Methods

Young (10-16 weeks), Adult (5-7 months), Aged (13-15 months), and Old (19-22 months) hamsters were used. Weights of bodies, testes, and epididymides were measured. Testes and epididymides were studied by histological microscopy. Sera were obtained to determine testosterone concentrations. Sperm were analyzed by video-microscopy.

Results

By aging, body weights increased but weights of testes and epididymides decreased. Most hamsters were normozoospermia, although several old hamsters were azoospermia. In testes and epididymides, desquamation and structures resembling residual bodies (SRRBs) were observed. Although desquamation was not always related to aging, SRRBs occurred by aging. Testosterone concentrations were not changed in normozoospermic hamsters, but it was significantly reduced in old azoospermic hamster. Aging significantly reduced sperm ability to exhibit hyperactivation. Additionally, aging significantly increased the straight-line velocity (VSL). P4, Mel, and 5-HT lessened the reduction in sperm hyperactivation and the increasing of VSL.

Conclusion

Aging reduces qualities of testes, epididymides, and sperm, and P4, Mel, and 5-HT recover reduced quality of sperm.

Is there a temporal trend in semen quality in Belgian candidate sperm donors and in sperm donors' fertility potential from 1995 onwards?

BACKGROUND

A recent meta-regression analysis reported a temporal trend in sperm count showing a significant decline in sperm count between 1973 and 2011. This decline is thought to affect fecundity. Moreover, semen quality is considered of key interest to public health given its association with all-cause male morbidity/mortality. The issue requires ongoing investigation due to geographical variation in semen quality and methodological errors in semen analysis.

OBJECTIVE

To study whether there is a temporal trend in semen quality in Belgian candidate sperm donors and in sperm donors' fertility potential.

MATERIALS AND METHODS

Retrospective analysis of samples provided by 439 candidate donors and pregnancy outcome in acceptors over a period of 23 years.

RESULTS

A total of 807 specimens from 439 candidate donors were examined from January 1995 to December 2017 (Table S1). Sub-analyses performed with regard to TSC from 2010 onwards (weighing) revealed a significant negative trend (R² =-0.033; β=-0.18; CI: -0.16 to 0.07; p < 0.05). We found a statistically significant association between year of donation and morphology (R² = 0.036; β= -0.19; CI: -0.26 to -0.08; p < 0.0001). The mean (±SD) clinical pregnancy rate per effective donor recruited (n = 104), defined as the number of women with a clinical pregnancy, per number of women who initiated treatment with a donor's spermatozoa, was 68.5 (± 24.9) %. This measure did not show a significant change in function of year of donation.

DISCUSSION

Candidate sperm donors represent a select group of men; as such, these results are not to be interpreted as representative for the general population.

CONCLUSION

The study did not show a significant change in sperm concentration or fertility potential in sperm donors over a period of 23 years. However, a negative trend was found for TSC from 2010 onwards. Also, the results show a significant decrease in ideal morphology over time.

Oxidative Stress and Reproductive Function in the Aging Male

With the delay of parenthood becoming more common, the age at which men father children is on the rise. While the effects of advanced maternal age have been well documented, only recently have studies started to focus on the impact of advanced paternal age (APA) in the context of male reproduction. As men age, the antioxidant defense system gradually becomes less efficient and elevated levels of reactive oxygen species (ROS) accumulate in spermatozoa; this can impair their functional and structural integrity. In this review, we present an overview of how oxidative stress is implicated in male reproductive aging by providing a summary of the sources and roles of ROS, the theories of aging, and the current animal and human studies that demonstrate the impacts of APA on the male germ line, the health of progeny and fertility, and how treatment with antioxidants may reverse these effects.

Postmortem non-directed sperm donation: quality matters

In our paper 'The ethical case for non-directed postmortem sperm donation' we argued that it would be ethical for men to donate sperm after death for use by strangers. In their thoughtful response Fredrick and Ben Kroon lay out practical concerns regarding our proposal. They raise issues regarding the quality of sperm collected postmortem based on empirical studies. Second, they claim that concerns about quality would make women unlikely to use sperm collected after death. In this response we explore issues of sperm quality in both living and dead donors. We consider whether there might be ways to ensure quality in both. Finally, we question whether quality should be a barrier to women choosing to use sperm donated after death.

Cyperus esculentus L. (tigernut) mitigates high salt diet-associated testicular toxicity in Wistar rats by targeting testicular steroidogenesis, oxidative stress and inflammation

High salt diet (HSD) impairs testicular function via oxidative stress. Cyperus esculentus contains antioxidants and improves testicular function. We investigated the protective effect of hydro-ethanolic extract of Cyperus esculentus on testicular function in HSD-fed Wistar rats. Twenty-five male Wistar rats (125-135 g) 8-9 weeks old were divided into five groups (n = 5): control, HSD-fed (8 % NaCl in feed), extract-treated (500 mg kg^-1  day^-1 ), HSD-fed +500 mg kg^-1  day^-1 of extract and HSD-fed +1,000 mg kg^-1  day^-1 of extract groups. Treatment lasted for 6 weeks. HSD decreased (p < .05) sperm parameters and serum reproductive hormones levels, while Cyperus esculentus extract improved (p < .05) sperm parameters, and serum testosterone and follicle-stimulating hormone levels in HSD-fed rats. The extract upregulated intra-testicular testosterone level and activities of 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-HSD, downregulated malondialdehyde and nitric oxide levels, and exhibited a dose-dependent decrease in pro-inflammatory cytokines, upregulation of activities of enzymatic antioxidants and increase in total antioxidant capacity in testes of HSD-fed rats. The extract at both doses improved Johnsen's score, Leydig and Sertoli cell counts and seminiferous tubular diameter in HSD-fed rats. Cyperus esculentus exhibited a dose-dependent mitigation of HSD-associated testicular dysfunction by targeting testicular steroidogenesis, oxidative stress and inflammation.

Bariatric Surgery Impact on Reproductive Hormones, Semen Analysis, and Sperm DNA Fragmentation in Men with Severe Obesity: Prospective Study

PURPOSE

Growing evidence in the literature suggests that obesity is capable of altering reproductive hormone levels and male fertility. Effects on classic semen parameters and sperm DNA fragmentation (SDF), however, have not been properly established. Additionally, the impact of bariatric surgery (BS) on those parameters is still controversial.

MATERIALS AND METHODS

In Phase 1, 42 patients with obesity and 32 fertile controls were submitted to reproductive hormone evaluation, semen analysis, and SDF testing. In Phase 2, patients with obesity were submitted to BS or clinical follow-up and were invited to 6-month revaluation.

RESULTS

Phase 1: Men with obesity have higher levels of estradiol, LH, and FSH and lower levels of total testosterone (TT) when compared with eutrophic fertile men. Additionally, they present worse semen parameters, with reduction in ejaculated volume and sperm concentration, worse sperm motility and morphology, and higher SDF. Phase 2: 32 patients returned to revaluation. Eighteen were submitted to BS (group S) and 14 were not submitted to any specific therapeutic regimen (group NS). In group S, TT more than doubled after surgery (294.5 to 604 ng/dL, p < 0.0001). Worsening of sperm concentration and total ejaculated sperm count were also noticed, and 2 patients became azoospermic after BS. SDF, however, improved after the procedure. No changes in the variables studied were observed in non-operated patients.

CONCLUSION

In this prospective study, we have found that BS results in improvements in reproductive hormone levels and SDF after 6-month follow-up. Sperm concentration, however, reduced after the procedure.

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.

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.

Decline in seminal quality in Indian men over the last 37 years

BACKGROUND

Since the first report of a decline in semen quality in 1974, there have been several reports of similar declines across populations. Despite some scattered reports of declining semen quality in the Indian sub-continent, comprehensive studies analyzing semen quality over the last few decades have not been undertaken. We undertook the present study to investigate the temporal trend in semen parameters in Indian populations over a period of 37 years (1979-2016).

METHODS

Publications providing semen analysis details for fertile and infertile men from the Indian sub-continent were collected by a thorough literature search. Semen quality data for 6466 normal fertile or presumptive normal men (from 119 studies/data sets) and 7020 infertile men (from 63 studies/data sets) published between 1979 and 2016 were retrieved. We undertook systematic review and quantitative analysis of mean sperm count, motility, normal morphology and other available parameters. Data were analyzed to estimate semen parameters reference values for Indian men and to assess temporal trends in infertile, fertile and all subjects.

RESULTS

Seminal quality shows a decreasing temporal trend and the decrease is higher in infertile than fertile males. In pooled analysis for all individuals, significant (p < 0.05 or < 0.001) declines in sperm concentration and normal morphology are observed; however, isolated analysis for each group shows declines without statistical significance. The mean (± SD) semen volume, sperm concentration, total motility, rapid linear progressive motility, normal sperm morphology and sperm viability for Indian fertile men are 2.88 ± 0.77 ml, 81.08 ± 29.21 million/ml, 66.37 ± 10.95%, 52.64 ± 15.78%, 56.68 ± 20.23% and 72.63 ± 8.31%, respectively, whereas in infertile these are 3.07 ± 1.27 ml, 37.94 ± 26.41 million/ml, 40.22 ± 13.76%, 26.79 ± 15.47%, 36.41 ± 21.66% and 55.25 ± 11.99%, respectively. The mean seminal parameter values were significantly lower (p < 0.001) in infertile as compared to fertile men, except semen volume.

CONCLUSIONS

Semen parameters in Indian men have declined with time and the deterioration is quantitatively higher in the infertile group. The study also provides reference values for semen parameters in Indian men.

Endocrine disruptors and testicular function

Despite concerns of the scientific community regarding the adverse effects of human exposure to exogenous man-made chemical substances or mixtures that interfere with normal hormonal balance, the so called "endocrine disruptors (EDs)", their production has been increased during the last few decades. EDs' extensive use has been implicated in the increasing incidence of male reproductive disorders including poor semen quality, testicular malignancies and congenital developmental defects such as hypospadias and cryptorchidism. Several animal studies have demonstrated that exposure to EDs during fetal, neonatal and adult life has deleterious consequences on male reproductive system; however, the evidence on humans remains ambiguous. The complexity of their mode of action, the differential effect according to the developmental stage that exposure occurs, the latency from exposure and the influence of the genetic background in the manifestation of their toxic effects are all responsible factors for the contradictory outcomes. Furthermore, the heterogeneity in the published human studies has hampered agreement in the field. Interventional studies to establish causality would be desirable, but unfortunately the nature of the field excludes this possibility. Therefore, future studies based on standardized guidelines are necessary, in order to estimate human health risks and implement policies to limit public exposure.

Associations of semen quality with non-essential heavy metals in blood and seminal fluid: data from the Environment and Male Infertility (EMI) study in Lebanon

BACKGROUND

Human exposure to environmental pollutants is widespread. It was suggested that exposure to non-essential heavy metals may adversely affect semen development in men.

PURPOSE

To evaluate associations between non-essential heavy metals in blood and seminal fluid and semen quality parameters in men.

METHODS

Male partners of heterosexual couples were included. The following elements were measured in blood and seminal fluid: lead (Pb), cadmium (Cd), arsenic (As), barium (Ba), mercury (Hg), and uranium (U) using ion-coupled plasma-mass spectrometry.

SETTING

The fertility clinic at the American University of Beirut Medical Center.

MAIN OUTCOME MEASURES

Semen quality parameters (volume, concentration, total count, progressive motility, viability, and normal morphology).

RESULTS

We found that participants with low-quality semen had significantly higher Cd and Ba concentrations in the seminal fluid than participants with normal-quality semen. We also observed significant associations between low sperm viability and higher blood Cd and Ba, as well as higher seminal Pb, Cd, Ba, and U. Furthermore, U concentrations in the seminal fluid were associated with increased odds ratios for below-reference progressive sperm motility and normal morphology.

CONCLUSIONS

Environmental exposures to Pb, Cd, Ba, and U appear to adversely influence sperm development in men. In non-occupationally exposed men, measurements of heavy metals in the seminal fluid may be more predictive of below-reference sperm quality parameters than in blood.

Temporal trends in sperm count: a systematic review and meta-regression analysis

BACKGROUND

Reported declines in sperm counts remain controversial today and recent trends are unknown. A definitive meta-analysis is critical given the predictive value of sperm count for fertility, morbidity and mortality.

OBJECTIVE AND RATIONALE

To provide a systematic review and meta-regression analysis of recent trends in sperm counts as measured by sperm concentration (SC) and total sperm count (TSC), and their modification by fertility and geographic group.

SEARCH METHODS

PubMed/MEDLINE and EMBASE were searched for English language studies of human SC published in 1981-2013. Following a predefined protocol 7518 abstracts were screened and 2510 full articles reporting primary data on SC were reviewed. A total of 244 estimates of SC and TSC from 185 studies of 42 935 men who provided semen samples in 1973-2011 were extracted for meta-regression analysis, as well as information on years of sample collection and covariates [fertility group ('Unselected by fertility' versus 'Fertile'), geographic group ('Western', including North America, Europe Australia and New Zealand versus 'Other', including South America, Asia and Africa), age, ejaculation abstinence time, semen collection method, method of measuring SC and semen volume, exclusion criteria and indicators of completeness of covariate data]. The slopes of SC and TSC were estimated as functions of sample collection year using both simple linear regression and weighted meta-regression models and the latter were adjusted for pre-determined covariates and modification by fertility and geographic group. Assumptions were examined using multiple sensitivity analyses and nonlinear models.

OUTCOMES

SC declined significantly between 1973 and 2011 (slope in unadjusted simple regression models -0.70 million/ml/year; 95% CI: -0.72 to -0.69; P < 0.001; slope in adjusted meta-regression models = -0.64; -1.06 to -0.22; P = 0.003). The slopes in the meta-regression model were modified by fertility (P for interaction = 0.064) and geographic group (P for interaction = 0.027). There was a significant decline in SC between 1973 and 2011 among Unselected Western (-1.38; -2.02 to -0.74; P < 0.001) and among Fertile Western (-0.68; -1.31 to -0.05; P = 0.033), while no significant trends were seen among Unselected Other and Fertile Other. Among Unselected Western studies, the mean SC declined, on average, 1.4% per year with an overall decline of 52.4% between 1973 and 2011. Trends for TSC and SC were similar, with a steep decline among Unselected Western (-5.33 million/year, -7.56 to -3.11; P < 0.001), corresponding to an average decline in mean TSC of 1.6% per year and overall decline of 59.3%. Results changed minimally in multiple sensitivity analyses, and there was no statistical support for the use of a nonlinear model. In a model restricted to data post-1995, the slope both for SC and TSC among Unselected Western was similar to that for the entire period (-2.06 million/ml, -3.38 to -0.74; P = 0.004 and -8.12 million, -13.73 to -2.51, P = 0.006, respectively).

WIDER IMPLICATIONS

This comprehensive meta-regression analysis reports a significant decline in sperm counts (as measured by SC and TSC) between 1973 and 2011, driven by a 50-60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand. Because of the significant public health implications of these results, research on the causes of this continuing decline is urgently needed.

Routine assessment of occupational exposure and its relation to semen quality in infertile men: a cross-sectional study

BACKGROUND/AIM

Concerns about the detrimental effects of occupational and environmental exposure on male reproductive function have been raised by reports of declining sperm quality over the last decades. The aim of this study was to investigate the association between altered semen parameters and exposure to occupational risk factors as assessed by questionnaire.

MATERIALS AND METHODS

We conducted a cross-sectional questionnaire-based study among a population of 2122 men who underwent andrological investigation for couple infertility. All participants were interviewed and their semen samples were analyzed. Information about medical history and occupational exposure was used to classify participants into exposed and unexposed groups.

RESULTS

Exposure to pesticides was associated with a significantly higher risk of asthenozoospermia (adjusted odds ratio [OR] = 1.6; 95% CI, 1.0-2.4) and necrozoospermia (OR = 2.6; 95% CI, 1.4-4.7). Exposure to cement was found to be correlated with a higher risk of oligozoospermia (OR = 1.1; 95% CI, 0.9-1.4). There was no association between semen impairment and exposure to solvents, excess heat, or mechanical vibrations.

CONCLUSION

We found an association between self-reported occupational exposure and altered semen parameters. These results support the usefulness of questionnaires for routine assessment and management of occupational exposures in infertile men.

Decline in sperm count in European men during the past 50 years

Purpose:

To investigate whether the sperm concentration of European men is deteriorating over the past 50 years of time.

Materials and Methods:

We analysed the data published in English language articles in the past 50 years in altering sperm concentration in European men.

Results:

A time-dependent decline of sperm concentration ( r = −0.307, p = 0.02) in the last 50 years and an overall 32.5% decrease in mean sperm concentration was noted.

Conclusion:

This comprehensive, evidence-based meta-analysis concisely presents the evidence of decreased sperm concentration in European male over the past 50 years to serve the scientific research zone related to male reproductive health.

Environmental pollutants: genetic damage and epigenetic changes in male germ cells

About a quarter of the human diseases occurs for exposure to air pollution. The male reproductive system, and especially spermatogenesis, seems to be particularly sensitive. As result, male infertility is increasing in industrial countries becoming a top priority for public health. In addition to psychological distress and economic constraints, poorer semen quality may have trans-generational effects including congenital malformations in the offspring and predispose to later onset adult diseases. Genetic and epigenetic alterations are involved in the failure of spermatogenesis. In this paper, we reviewed the major evidences of the effects of air pollutants on male infertility as well as the role of sperm DNA damage and epigenetic changes in affecting spermatogenesis. A better knowledge on the effects of air contaminants on the molecular mechanisms leading to infertility is of huge importance to help clinicians in identifying the cause of infertility but above all, in defining preventive and therapeutic protocols.

Tobacco smoking is associated with decreased semen quality

BACKGROUND

Tobacco smoking is a public health issue and has been implicated in adverse reproductive outcomes including semen quality. Available data however provides conflicting findings. The objective of this study was to evaluate the effect of tobacco smoking on semen quality among men in Ghana.

METHODS

In this study, a total of 140 subjects were recruited, comprising 95 smokers and 45 non-smokers. Smokers were further categorized into mild, moderate and heavy smokers. Semen parameters such as sperm concentration, motility, viability and normal morphology were measured according to the World Health Organisation criteria.

RESULTS

The study showed that smokers had significantly lower semen volume, sperm concentration, sperm motility, total sperm count, sperm morphology, free testosterone and follicle stimulating hormone (p <0.05 respectively), compared with non-smokers. Smokers were at a higher risk of developing oligospermia, asthenozoospermia and teratozoospermia (OR = 3.1, 4.2 and, 4.7; p <0.05) than non-smokers.

CONCLUSION

Results demonstrated a decline in semen quality in a dose dependent tobacco smoking manner.

The Disappearing Sperms: Analysis of Reports Published Between 1980 and 2015

Reports regarding the changes in sperm concentration in different counties of the world are inconsistent. Furthermore, the reports that sprung up from specific epidemiological and experimental examinations did not include data of prior studies or geographical variations. The current study, following a previous report of massive fall in semen volume over the past 33 years, attempts to delineate the trend of altering sperm concentrations and factors responsible for this by reviewing article published from 1980 to July 2015 with geographic differences. The current study identified an overall 57% diminution in mean sperm concentration over the past 35 years ( r = -.313, p = .0002), which, when analyzed for each geographical region, identified a significant decline in North America, Europe, Asia, and Africa. An increasing trend of sperm concentration was identified only in Australia. The association of male age with such a trend ( R² = .979) is reported. The authors also correlated male fertility with sperm concentration. Thus, this comprehensive, evidence-based literature review aims to concisely and systematically present the available data on sperm concentration from 1980 to 2015, as well as to statistically analyze the same and correlate male health with the declining pattern of sperm count in a single scientific review to serve the scientific research zone related to reproductive health. It points to the threat of male infertility in times ahead.

Changes in the semen quality among 5739 men seeking infertility treatment in Northern Norway over past 20 years (1993–2012)

Semen quality plays a pivotal role in sustaining the fertility rate and healthy population growth. Therefore, assessment of temporal trends in the semen quality provides valuable public health information. We analyzed the semen quality parameters of 5739 North Norwegian men among consecutive couples attending the fertility clinic of University Hospital of North Norway for investigation and/or treatment from 1993 to 2012. The seminal fluid volume, sperm concentration, and total sperm count were found to have gradually decreased during the past 20 years. The proportion of hypospermic, azoospermic, and oligozoospermic men had increased by 24.6% ( p < 0.001), 109.5% ( p < 0.001), and 9.5% ( p = 0.05), respectively, in the last decade (2003–2012) compared to the first decade (1993–2002). The parameters of semen quality are rapidly deteriorating in North Norwegian men seeking fertility treatment.

Association between air pollution and sperm quality: A systematic review and meta-analysis

Exposure to ambient air pollution has been clearly linked to adverse reproductive outcome and fecundation index, but its effects on male semen quality are still uncertain. In this study, we reviewed information from ten studies to get the qualitative evidence of the influence of the ambient air pollution on sperm quality and collected data from six of the ten studies to conduct meta-analysis. The original studies classified participants into different exposure levels and the highest and lowest expose levels were chosen as high expose and low expose groups, respectively. The random-effect model was used in the meta-analysis with the weight mean difference (WMD) as the measure indicator. The WMDs (95% confidence intervals, CIs) of sperm volume, sperm count, semen concentration, sperm progressive motility, total motility, and normal morphology were 0.09 (-0.04, 0.23), 0.46 (-4.47, 5.39), -8.21 (-20.38, 3.96), -7.76 (-16.26, 0.74), -7.61 (-16.97, 1.74) and -3.40 (-7.42, 0.62), respectively. In conclusion, although the differences are not statistically significant between the two groups, the overall trends and evidence from this review indicate the chronic exposure to ambient pollutants at high level may alter men sperm quality.

Semen profiles of young men involved as bicycle taxi cyclists in Mangochi District, Malawi: A case-control study

AIM

The purpose of this study was to evaluate the semen profiles of bicycle taxi cyclists and healthy controls in Mangochi district, Malawi.

METHODS

Semen samples were collected from young bicycle taxi cyclists after two to three days of sexual abstinence. A control group, comprising young men who were not bicycle taxi operators also submitted semen samples. Samples were left to liquefy for 30 minutes before measurements were conducted of volume, concentration, total motility, and progressive motility. This was followed by preparation of morphology slides. Light microscopy was used for sperm analysis.

RESULTS

Semen parameters such as volume (1.66 ± 0.18 mL vs. 3.64 ± 0.17 mL; p = 0.0001), concentration (28.31 ± 4.33 x 106/mL vs. 54.95 ± 5.93 × 106/mL; p = 0.02) , total motility (56.98% ± 8.22% vs. 56.98% ± 8.22%; p = 0.03), progressive motility (22.57% ± 3.35% vs. 59.69% ± 4.82%; p = 0.004), and morphology (6.98% ± 3.23% vs. 19.73% ± 2.32%; p = 0.006) were significantly reduced in the bicycle taxi cyclists compared to the healthy controls.

CONCLUSION

In this case-control study, bicycle taxi operators had lower semen volume, concentration, total motility, and progressive motility, as well as a higher concentration of abnormally shaped spermatocytes, compared to healthy controls.

The histone demethylase KDM1A is essential for the maintenance and differentiation of spermatogonial stem cells and progenitors

Little is known of the fundamental processes governed by epigenetic mechanisms in the supplier cells of spermatogenesis, the spermatogonial stem cells (SSCs). The histone H3 lysine demethylase KDM1A is expressed in spermatogonia. We hypothesized that KDM1A serves in transcriptional regulation of SSCs and fertility. Using a conditional deletion of Kdm1a [conditional knockout (cKO)] in mouse spermatogonia, we determined that Kdm1a is essential for spermatogenesis as adult cKO males completely lack germ cells. Analysis of postnatal testis development revealed that undifferentiated and differentiating spermatogonial populations form in Kdm1a-cKO animals, yet the majority fail to enter meiosis. Loss of germ cells in the cKO was rapid with none remaining by postnatal day (PND) 21. To gain insight into the mechanistic implications of Kdm1a ablation, we isolated PND 6 spermatogonia enriched for SSCs and analyzed their transcriptome by RNA sequencing. Loss of Kdm1a was associated with altered transcription of 1206 genes. Importantly, differentially expressed genes between control and Kdm1a-cKO animals included those that are essential for SSC and progenitor maintenance and spermatogonial differentiation. The complete loss of fertility and failure to establish spermatogenesis indicate that Kdm1a is a master controller of gene transcription in spermatogonia and is required for SSC and progenitor maintenance and differentiation.

The Association between Dietary Patterns and Semen Quality in a General Asian Population of 7282 Males

OBJECTIVE

To explore the associations between different dietary patterns and semen quality in a general Asian male population.

METHODS

Cross-sectional study. Healthy Taiwanese men aged 18 years or older who participated in a standard medical screening program from 2008-2013 run by a private firm were included in this study. Semen parameters including sperm concentration (SC), total sperm motility (TSM), progressive motility (PRM) and normal sperm morphology (NSM) were recorded. A dietary questionnaire was used to categorize the participants into 5 groups: "Healthy diet", "Western diet", "High-carbohydrate diet", "High sweet snacks & sugar-sweetened drinks" and "High-sodium diet".

RESULTS

A total of 7282 men completed the questionnaire regarding dietary pattern, and examination of anthropometric indexes was performed and laboratory data were obtained. A high intake of a "Western diet" resulted in statistically linear declines of SC and NSM (P < 0.001 and P < 0.001). Similarly, a greater intake of "High sweet snacks & sugar-sweetened drinks" was associated with a lower SC (P = 0.001). Increased intake of a "High-carbohydrate diet" was related to higher prevalences of abnormal TSM and PRM (P = 0.012 and P = 0.025). Similarly, a greater intake of a "High-sodium diet" was correlated with an elevated prevalence of abnormal NSM (P = 0.035).

CONCLUSIONS

This study showed that a greater intake of a "Western diet" is associated with poorer SC and NSM, a "High sweet snacks and sugar-sweetened drinks" intake is correlated with a lower SC, and high-carbohydrate food is related to elevated prevalences of abnormal TSM and PRM.

Decline in semen quality among infertile men in Brazil during the past 10 years

PURPOSE

To investigate whether the semen quality of men undergoing conventional semen analysis is deteriorating over time.

MATERIALS AND METHODS

We analyzed and compared the sperm count, motility and morphology of 2300 semen samples provided by males undergoing conventional seminal analysis, from years 2000 to 2002 and 2010 to 2012. The incidences of severe oligozoospermia and azoospermia over time were also compared.

RESULTS

A total of 764 sperm samples were analyzed in 2000-2002 and 1536 in 2010-2012. Over time, the mean sperm concentration/ml decreased significantly from 61.7 million in 2000-2002 to 26.7 million in 2010-2012 (R2 = 11.4%, p < 0.001), the total sperm concentration decreased significantly from 183.0 million to 82.8 million (R2 = 11.3%, p < 0.001), and the percentage of normal forms decreased significantly from 4.6% to 2.7% (R2 = 9.8%, p < 0.001). The incidence of severe oligozoospermia significantly increased from 15.7% to 30.3% (OR: 1.09, p < 0.001) and the incidence of azoospermia increased from 4.9% to 8.5% (OR: 1.06, p = 0.001).

CONCLUSIONS

This study demonstrated a significant time-related decline in semen quality of infertile patients. This finding might have implications on fertility and emphasizes the need for further studies addressing subject's life-style in order to find and reduce the causative agents. Future prospective and multicenter studies including representative samples of the general population are needed to confirm whether semen quality is really declining.

Semen Quality Assessment in Fertile Men in Madrid During the Last 3 Decades

OBJECTIVE

To evaluate semen quality of men with proven fertility in Spain over the last 3 decades.

METHODS

We conduct a retrospective analysis of ejaculate samples of 992 men between 1985 and 2009. All patients had proven fertility as demonstrated by fathering at least 2 children and a semen analysis performed before they underwent vasectomy. A standardized procedure was used for the semen analysis. Semen volume, total sperm count, sperm concentration, motility, and percentage of morphologically normal spermatozoa were assessed. Mean values were calculated by examining microscopic fields of 100 spermatozoa.

RESULTS

Statistically significant differences were found in all semen parameters analyzed. For the periods 1985-1990, 1990-2000, and 2000-2009, the mean (standard deviation [SD]) sperm concentration was 27.7 (22.97), 20.73 (14.79), and 20.18 (20.79) × 10(6) (P <.0001). The mean (SD) progressive motility for each period was 53.19 (20.35), 47.22 (15.84), and 40.57 (15.15; P <.0001). The mean (SD) normal-shaped spermatozoa for each period was 67.69 (10.24), 58.87 (14.67), and 51.02 (15.76; P <.0001). Multivariate analysis using a logistic regression model showed that age had no significant effect in the variation of semen parameters at the cut-points analyzed, except for normal forms at percentile 25 (P = .001). Multivariate analysis revealed a trend for decline of semen in sperm concentration, progressive and nonprogressive motility, and the percentage of morphologically normal spermatozoa (P = .001-.002).

CONCLUSION

Over the last 3 decades, a decline in semen quality was found in all the parameters analyzed in Spanish men with proven fertility.

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.

Paternal age and assisted reproductive outcomes in ICSI donor oocytes: is there an effect of older fathers?

STUDY QUESTION

Does paternal age affect semen quality and reproductive outcomes in oocyte donor cycles with ICSI?

SUMMARY ANSWER

Paternal age is associated with a decrease in sperm quality, however it does not affect either pregnancy or live birth rates in reproductive treatments when the oocytes come from donors <36 years old and ICSI is used.

WHAT IS KNOWN ALREADY

The weight of evidence suggest that paternal age is associated with decreasing sperm quality, but uncertainty remains as to whether reproductive outcomes are affected. Although developed to treat severe sperm factor infertility, ICSI is gaining popularity and is often used even in the presence of mild male factor infertility.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study spanning the period between February 2007 and June 2010. A total of 4887 oocyte donation cycles were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Fertilization was carried out by ICSI in all cycles included, and the semen sample used was from the male partner in all cases. The association of male age with semen parameters (volume, concentration, percentage of motile spermatozoa) was analyzed by multiple analysis of covariance. The association of male age with reproductive outcomes (biochemical pregnancy, miscarriage, ongoing pregnancy and live birth rate) was modeled by logistic regression, where the following covariates were introduced: donor age, recipient age, semen state (fresh versus frozen) and number of transferred embryos (3 and 2 versus 1).

MAIN RESULTS AND THE ROLE OF CHANCE

We identified a significant relationship between paternal age and all sperm parameters analyzed: for every 5 years of age, sperm volume decreases by 0.22 ml (P < 0.001), concentration increases by 3.1 million sperm/ml (P = 0.003) and percentage motile spermatozoa decreases by 1.2% (P < 0.001). No differences were found in reproductive outcomes (biochemical pregnancy, miscarriage, clinical pregnancy, ongoing pregnancy and live birth) among different male age groups.

LIMITATIONS, REASONS FOR CAUTION

The use of donor oocytes, while extremely useful in highlighting the role of male age in reproductive outcomes, limits the generalization of our results to a population of young women with older male partners. No data were available on perinatal and obstetrical outcomes of these pregnancies. Most (75%) cycles used frozen/thawed sperm samples which might have introduced a bias owing to loss of viability after thawing. ICSI was performed in all cycles to control for fertilization method; this technique could mask the natural fertilization rate of poorer sperm samples. Furthermore, we did not use stringent ICSI indications; and our data are therefore not generalizable to cases where only severe male factor is considered. However, male patients were of different racial background, thus allowing generalizing our results to a wider patient base.

WIDER IMPLICATIONS OF THE FINDINGS

Our study suggests that paternal age does not affect reproductive outcomes when the oocyte donor is <36 years of age, indicating that ICSI and oocyte quality can jointly overcome the lower reproductive potential of older semen.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported in part by Fundació Privada EUGIN. The authors have no conflicts of interest to declare.

Drinking-water disinfection by-products and semen quality: a cross-sectional study in China

BACKGROUND

Exposure to disinfection by-products (DBPs) has been demonstrated to impair male reproductive health in animals, but human evidence is limited and inconsistent.

OBJECTIVE

We examined the association between exposure to drinking-water DBPs and semen quality in a Chinese population.

METHODS

We recruited 2,009 men seeking semen analysis from the Reproductive Center of Tongji Hospital in Wuhan, China, between April 2011 and May 2012. Each man provided a semen sample and a urine sample. Semen samples were analyzed for sperm concentration, sperm motility, and sperm count. As a biomarker of exposure to drinking-water DBPs, trichloroacetic acid (TCAA) was measured in the urine samples.

RESULTS

The mean (median) urinary TCAA concentration was 9.58 (7.97) μg/L (interquartile range, 6.01-10.96 μg/L). Compared with men with urine TCAA in the lowest quartile, increased adjusted odds ratios (ORs) were estimated for below-reference sperm concentration in men with TCAA in the second and fourth quartiles (OR = 1.79; 95% CI: 1.19, 2.69 and OR = 1.51; 95% CI: 0.98, 2.31, respectively), for below-reference sperm motility in men with TCAA in the second and third quartiles (OR = 1.46; 95% CI: 1.12, 1.90 and OR = 1.30; 95% CI: 1.00, 1.70, respectively), and for below-reference sperm count in men with TCAA in the second quartile (OR 1.62; 95% CI: 1.04, 2.55). Nonmonotonic associations with TCAA quartiles were also estimated for semen parameters modeled as continuous outcomes, although significant negative associations were estimated for all quartiles above the reference level for sperm motility.

CONCLUSION

Our findings suggest that exposure to drinking-water DBPs may contribute to decreased semen quality in humans.

High frequency of TTTY2-like gene-related deletions in patients with idiopathic oligozoospermia and azoospermia

Genes located on Y chromosome and expressed in testis are likely to be involved in spermatogenesis. TTTY2 is a Y-linked multicopy gene family of unknown function that includes TTTY2L2A and TTTY2L12A at Yq11 and Yp11 loci respectively. Using PCR amplification, we screened for TTTY2L2A- and TTTY2L12A-associated deletions, in 94 Greek men with fertility problems. Patients were divided into three groups as following: group A (n = 28) included men with idiopathic moderate oligozoospermia, group B (n = 34) with idiopathic severe oligozoospermia and azoospermia, and group C (n = 32) with oligo- and azoospermia of various known etiologies. No deletions were detected in group C patients and 50 fertile controls. However, two patients from group A had deletions in TTTY2L2A (7.1%) and six in TTTY2L12A (21.4%), whereas from group B, four patients had deletions in TTTY2L2A (11.8%) and 10 in TTTY2L12A (29.4%). In addition, five patients from both groups A and B (8%) appeared to have deletions in both studied TTTY2 genes, although these are located very far apart. These results indicate that the TTTY2 gene family may play a significant role in spermatogenesis and suggest a possible mechanism of nonhomologous recombinational events that may cause genomic instability and ultimately lead to male infertility.

In vitro exposure of Leydig cells to an environmentally relevant mixture of organochlorines represses early steps of steroidogenesis

Leydig cell steroidogenesis is mainly regulated by LH via increased cAMP production leading to STAR protein activation. STAR is essential for cholesterol shuttling inside mitochondria where steroidogenesis is initiated. Accumulating evidence suggest that persistent organochlorine compounds disrupt testicular function, but the mechanism of action remains poorly characterized. Here we report that in vitro exposure of MA-10 and MLTC-1 Leydig cells to an environmentally relevant mixture of 15 organochlorines impairs steroidogenesis. While having no effect on cell viability and basal steroid production, the organochlorine mixture caused a 50% decrease in cAMP-induced progesterone production. The mixture also reduced cAMP-induced 30 kDa STAR protein by 50% while having no effect on basal STAR protein. Basal or cAMP-induced Star mRNA levels and promoter activity were unaffected by the mixture, indicating that the organochlorine mixture acted at the translational/posttranslational level. Further supporting this is the fact that in COS-7 cells overexpressing STAR, the organochlorine mixture caused a decrease in the 30 kDa form of STAR and an accumulation of the 37 kDa forms. In addition to STAR, we found that the organochlorine mixture also decreases the levels of CYP11A1 and ADXR, two proteins essential for the conversion of cholesterol into pregnenolone. In conclusion, our data show that organochlorine exposure disrupts Leydig cell function by targeting different components of the steroidogenic pathway.

Reproductive parameters and oxidative stress status of male rats fed with low and high salt diet

BACKGROUND:

Deficiency of minerals and micronutrients has been reported to impair the process of spermatogenesis. Historically, salt has been used by women on their husbands to increase their libido, however, the role of salt diet on sperm parameters are yet to be ascertained.

AIM:

The present study was designed to determine the effect of low and high salt diet on sperm parameters, oxidative status and reproductive hormone levels of male rats.

MATERIALS AND METHODS:

A total of 18 rats were divided into three groups: Group I: (control) received 0.3% salt diet, Group II: low salt (received 0.14% salt diet) and Group III: high salt (received 8% salt diet). All animals were treated for 6 weeks; after which epididymal sperm parameters; oxidative stress markers (malondialdehyde, glutathione, catalase and superoxide dismutase) in the testes and epididymal tissues, as well as follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone levels were determined.

RESULTS:

The results showed decreased sperm count in the low salt diet rats while increased sperm count was observed in the high salt diet treated rats. Both low salt and high salt diet fed rats exhibited increased abnormal sperm cells and increased epididymal oxidative stress when compared with their respective control. FSH and testosterone levels were increased in the high salt fed rats while LH level was decreased when compared with the control values.

CONCLUSION:

This study suggests that both low and high salt diet play a negative role in the fertility of male rats.

Shedding light on the controversy surrounding the temporal decline in human sperm counts: a systematic review

We systematically examined the evidence of declining sperm counts and the hypothesis that an increased exposure to environmental pollutants is responsible for such decline. Search engines, including PUBMED, MEDLINE, EMBASE, BIOSIS, and Cochrane library, were used to identify epidemiologic studies published from 1985 to 2013. We concluded that there is no enough evidence to confirm a worldwide decline in sperm counts. Also, there seems to be no scientific truth of a causative role for endocrine disruptors in the temporal decline of sperm production. Such assumptions are based on few meta-analyses and retrospective studies, while other well-conducted researches could not confirm these findings. We acknowledge that difficult-to-control confounding factors in the highly variable nature of semen, selection criteria, and comparability of populations from different time periods in secular-trend studies, the quality of laboratory methods for counting sperm, and apparently geographic variations in semen quality are the main issues that complicate the interpretation of the available evidence. Owing to the importance of this subject and the uncertainties still prevailing, there is a need not only for continuing monitoring of semen quality, reproductive hormones, and xenobiotics, but also for a better definition of fecundity.