Male fertility as a marker for health

A systematic review of interventions to improve male knowledge of fertility and fertility-related risk factors

Male infertility is a global health concern. The effectiveness of interventions developed to improve males' knowledge of fertility regulation and fertility-related risk factors remains unclear. This systematic review aimed to synthesize and evaluate the evidence for these interventions. Four databases were searched from inception to June 2023. Eligible studies examined interventions to increase fertility knowledge among presumed fertile males aged ≥16 years of age. Conference abstracts, protocols and studies without sex-disaggregated results for males were excluded. A narrative synthesis without meta-analysis was performed. A total of 4884 records were identified. Five studies (reported in six publications), all conducted in high-income countries, were included. Two were randomized control trials, and three were experimental studies. Interventions were delivered in person by a health professional (n = 3), online and via a mobile app. All studies showed a significant improvement in knowledge of fertility or fertility-related risk factors from baseline to follow-up. The largest improvement was observed for secondary and vocational students. A moderate, long-term retainment of knowledge was observed at two-year follow-up in one study. Available evidence suggests interventions to improve males' fertility knowledge are effective, particularly for younger, less educated males.

The Association Between Male Viral Infections and Infertility: A Systematic Review and Meta-Analysis

Infertility affects approximately one-sixth of couples worldwide, with male factors contributing to half of all cases. However, infections, particularly those of reproductive tract, are increasingly recognized as important contributors to male infertility. Therefore, in this meta-analysis, we focused on the impact of various viral infections on male infertility. We searched PubMed, Embase, Web of Science and Cochrane Library on 20 October 2023. And included 135 studies involving 30,298 men of reproductive age. We found that the human papilloma virus (HPV)-infected group had a significantly higher DNA fragmentation index (DFI) than the non-infected group, with a mean difference (MD) of 5.64 (95% CI: 3.74-7.54). Conversely, the HPV-infected group had significantly lower sperm count, concentration, viability and normal morphology. Other viruses that affect semen quality include hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). HBV significantly decreased fertilization rate, with an odds ratio (OR) of 0.86 (95% CI: 0.76-0.99). HPV associated with lower clinical pregnancy rate (OR: 0.31 [95% CI: 0.16-0.62]) and higher miscarriage rate (OR: 5.28 [95% CI: 2.02-13.78]). Additionally, the fertility treatment group had a significantly higher rate of HPV infection (OR: 1.85 [95% CI: 1.10-3.12]) and adeno-associated virus (AAV) infection (OR: 8.49 [95% CI: 2.66-27.10]) than the fertility group. Conclusively, most viral infections affect semen quality, while HBV and HPV may affect assisted reproductive technology (ART) outcomes. HPV and AAV are risk factors for infertility.

Diabetes and male fertility disorders

Couple infertility is a common condition, defined as being unable to conceive after 12 months of regular unprotected sexual intercourse. Male Factor Infertility (MFI) is responsible, alone or in combination with female factors, for about half of the overall cases of couple infertility. MFI is gradually increasing in prevalence, with a notable decline in semen parameters over the last decades. The aetiologies behind the finding of decreasing sperm counts are difficult to pinpoint but might be due in part to increasing rates of overweight and obesity in men of childbearing age. Diabetes mellitus (DM) is a common and chronic metabolic disease, whose prevalence is also gradually increasing, rising up to 10% of the population. The International Diabetes Federation estimates that there are currently more than 500 million people living with DM worldwide, the vast majority of whom suffering from type 2 DM (T2DM). There is growing awareness of the relationship between unhealthy lifestyle, in particular unhealthy diet, and MFI. Starting from all these premises, the aim of this narrative review is to describe the current evidence on the link between DM and MFI, both in terms of DM as a cause of/a risk factor for MFI and of MFI as a possible predictive marker for T2DM. Finally, we will discuss the risk of DM as a consequence of the therapy of MFI or assisted reproductive techniques.

Male infertility risk and plasma lipidome: a Mendelian randomization study

Background

In recent years, the decline in sperm quality in men has become a global trend. There is a close relationship between sperm quality and pregnancy outcome. There is a large body of literature supporting the role of plasma lipidome in male infertility, while the complex mechanisms between them and male infertility are still less clear. Systematic study of the causal relationship between plasma lipidome and MI can help to provide new therapeutic ideas and targets for male infertility.

Methods

In this study, we used a two-sample Mendelian randomization analysis based on Genome-wide association studies pooled data of 179 causal relationships between plasma lipidome and male infertility. We used employed the inverse variance weighted method as the main analysis to assess causality between exposure and outcome, in addition to MR-Egger, Weighted median as complementary methods, and tests for multiplicity and heterogeneity.

Results

We identified 13 plasma lipidome comprising 4 types of plasma lipidome that were associated with male infertility. Among these, 9 plasma lipidome were found to be protective factors, while 4 were risk factors. Notably, the largest proportion of these plasma lipidome were triglyceride types, with Sphingomyelin (d40:1) exhibiting the strongest association with male infertility.

Conclusion

These findings contribute to the current better understanding of male infertility and provide new perspectives on the underlying etiology of male infertility as well as prevention and treatment strategies. In addition, clinical trial validation is needed to assess the potential of these plasma lipidome as biomarkers.

Correlation between viral infections in male semen and infertility: a literature review

Infertility affects approximately one-sixth of couples globally, with the incidence of male infertility steadily increasing. However, our understanding of the impact of viral infections on fertility remains limited. This review consolidates findings from previous studies, outlining 40 viruses identified in human semen and summarizing their key characteristics, modes of transmission, and their effects on both the reproductive and endocrine systems. Furthermore, it elucidates potential pathogenic mechanisms and treatment prospects of viruses strongly associated with male infertility. This synthesis will enhance our comprehension of how viral infections influence male reproductive health, offering valuable insights for future research as well as the diagnosis and treatment of infectious infertility.

Unraveling the Genetic Basis of Combined Deafness and Male Infertility Phenotypes through High-Throughput Sequencing in a Unique Cohort from South India

The co-occurrence of sensorineural hearing loss and male infertility has been reported in several instances, suggesting potential shared genetic underpinnings. One such example is the contiguous gene deletion of CATSPER2 and STRC genes, previously associated with deafness-infertility syndrome (DIS) in males. Fifteen males with both hearing loss and infertility from southern India after exclusion for the DIS contiguous gene deletion and the FOXI1 gene mutations are subjected to exome sequencing. This resolves the genetic etiology in four probands for both the phenotypes; In the remaining 11 probands, two each conclusively accounted for deafness and male infertility etiologies. Genetic heterogeneity is well reflected in both phenotypes. Four recessive (TRIOBP, SLC26A4, GJB2, COL4A3) and one dominant (SOX10) for the deafness; six recessive genes (LRGUK, DNAH9, ARMC4, DNAH2, RSPH6A, and ACE) for male infertility can be conclusively ascribed. LRGUK and RSPH6A genes are implicated earlier only in mice models, while the ARMC4 gene is implicated in chronic destructive airway diseases due to primary ciliary dyskinesia. This study would be the first to document the role of these genes in the male infertility phenotype in humans. The result suggests that deafness and infertility are independent events and do not segregate together among the probands.

Interplay between male gonadal function and overall male health

The process-of-male reproduction is intricate, and various medical conditions-have the potential to disrupt spermatogenesis. Moreover, infertility in males can serve as an indicator of-potential future health issue. Numerous conditions with systemic implications have been identified, encompassing genetic factors (such as Klinefelter Syndrome), obesity, psychological stress, environmental factors, and others. Consequently, infertility assessment-presents an opportunity for comprehensive health counseling, extending-beyond discussions about reproductive goals. Furthermore, male infertility has been suggested as a harbinger of future health problems, as poor semen quality and a diagnosis of-male infertility are associated with an increased risk of hypogonadism, cardiometabolic disorders, cancer, and even mortality. This review explores the existing-literature on the relationship between systemic illnesses and male fertility, impacting both clinical-outcomes and semen parameters. The majority of the literature analyzed, which compared gonadal function with genetic, chronic, infectious or tumoral diseases, confirm the association between overall male health and infertility.

Describing patterns of familial cancer risk in subfertile men using population pedigree data

STUDY QUESTION

Can we simultaneously assess risk for multiple cancers to identify familial multicancer patterns in families of azoospermic and severely oligozoospermic men?

SUMMARY ANSWER

Distinct familial cancer patterns were observed in the azoospermia and severe oligozoospermia cohorts, suggesting heterogeneity in familial cancer risk by both type of subfertility and within subfertility type.

WHAT IS KNOWN ALREADY

Subfertile men and their relatives show increased risk for certain cancers including testicular, thyroid, and pediatric.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort of subfertile men (N = 786) was identified and matched to fertile population controls (N = 5674). Family members out to third-degree relatives were identified for both subfertile men and fertile population controls (N = 337 754). The study period was 1966-2017. Individuals were censored at death or loss to follow-up, loss to follow-up occurred if they left Utah during the study period.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Azoospermic (0 × 106/mL) and severely oligozoospermic (<1.5 × 106/mL) men were identified in the Subfertility Health and Assisted Reproduction and the Environment cohort (SHARE). Subfertile men were age- and sex-matched 5:1 to fertile population controls and family members out to third-degree relatives were identified using the Utah Population Database (UPDB). Cancer diagnoses were identified through the Utah Cancer Registry. Families containing ≥10 members with ≥1 year of follow-up 1966-2017 were included (azoospermic: N = 426 families, 21 361 individuals; oligozoospermic: N = 360 families, 18 818 individuals). Unsupervised clustering based on standardized incidence ratios for 34 cancer phenotypes in the families was used to identify familial multicancer patterns; azoospermia and severe oligospermia families were assessed separately.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to control families, significant increases in cancer risks were observed in the azoospermia cohort for five cancer types: bone and joint cancers hazard ratio (HR) = 2.56 (95% CI = 1.48-4.42), soft tissue cancers HR = 1.56 (95% CI = 1.01-2.39), uterine cancers HR = 1.27 (95% CI = 1.03-1.56), Hodgkin lymphomas HR = 1.60 (95% CI = 1.07-2.39), and thyroid cancer HR = 1.54 (95% CI = 1.21-1.97). Among severe oligozoospermia families, increased risk was seen for three cancer types: colon cancer HR = 1.16 (95% CI = 1.01-1.32), bone and joint cancers HR = 2.43 (95% CI = 1.30-4.54), and testis cancer HR = 2.34 (95% CI = 1.60-3.42) along with a significant decrease in esophageal cancer risk HR = 0.39 (95% CI = 0.16-0.97). Thirteen clusters of familial multicancer patterns were identified in families of azoospermic men, 66% of families in the azoospermia cohort showed population-level cancer risks, however, the remaining 12 clusters showed elevated risk for 2-7 cancer types. Several of the clusters with elevated cancer risks also showed increased odds of cancer diagnoses at young ages with six clusters showing increased odds of adolescent and young adult (AYA) diagnosis [odds ratio (OR) = 1.96-2.88] and two clusters showing increased odds of pediatric cancer diagnosis (OR = 3.64-12.63). Within the severe oligozoospermia cohort, 12 distinct familial multicancer clusters were identified. All 12 clusters showed elevated risk for 1-3 cancer types. An increase in odds of cancer diagnoses at young ages was also seen in five of the severe oligozoospermia familial multicancer clusters, three clusters showed increased odds of AYA diagnosis (OR = 2.19-2.78) with an additional two clusters showing increased odds of a pediatric diagnosis (OR = 3.84-9.32).

LIMITATIONS, REASONS FOR CAUTION

Although this study has many strengths, including population data for family structure, cancer diagnoses and subfertility, there are limitations. First, semen measures are not available for the sample of fertile men. Second, there is no information on medical comorbidities or lifestyle risk factors such as smoking status, BMI, or environmental exposures. Third, all of the subfertile men included in this study were seen at a fertility clinic for evaluation. These men were therefore a subset of the overall population experiencing fertility problems and likely represent those with the socioeconomic means for evaluation by a physician.

WIDER IMPLICATIONS OF THE FINDINGS

This analysis leveraged unique population-level data resources, SHARE and the UPDB, to describe novel multicancer clusters among the families of azoospermic and severely oligozoospermic men. Distinct overall multicancer risk and familial multicancer patterns were observed in the azoospermia and severe oligozoospermia cohorts, suggesting heterogeneity in cancer risk by type of subfertility and within subfertility type. Describing families with similar cancer risk patterns provides a new avenue to increase homogeneity for focused gene discovery and environmental risk factor studies. Such discoveries will lead to more accurate risk predictions and improved counseling for patients and their families.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by GEMS: Genomic approach to connecting Elevated germline Mutation rates with male infertility and Somatic health (Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): R01 HD106112). The authors have no conflicts of interest relevant to this work.

TRIAL REGISTRATION NUMBER

N/A.

Mixtures of per- and polyfluoroalkyl substances (PFAS) alter sperm methylation and long-term reprogramming of offspring liver and fat transcriptome

Male fertility has been declining worldwide especially in countries with high levels of endocrine disrupting chemicals (EDCs). Per- and polyfluorinated alkyl Substances (PFAS) have been classified as EDCs and have been linked to adverse male reproductive health. The mechanisms of these associations and their implications on offspring health remain unknown. The aims of the current study were to assess the effect of PFAS mixtures on the sperm methylome and transcriptional changes in offspring metabolic tissues (i.e., liver and fat). C57BL/6 male mice were exposed to a mixture of PFAS (PFOS, PFOA, PFNA, PFHxS, Genx; 20 µg/L each) for 18-weeks or water as a control. Genome-wide methylation was assessed on F0 epidydimal sperm using reduced representation bisulfite sequencing (RRBS) and Illumina mouse methylation array, while gene expression was assessed by bulk RNA sequencing in 8-week-old offspring derived from unexposed females. PFAS mixtures resulted in 2,861 (RRBS) and 83 (Illumina) sperm DMRs (q < 0.05). Functional enrichment revealed that PFAS-induced sperm DMRs were associated with behavior and developmental pathways in RRBS, while Illumina DMRs were related to lipid metabolism and cell signaling. Additionally, PFAS mixtures resulted in 40 and 53 differentially expressed genes (DEGs) in the liver and fat of males, and 9 and 31 DEGs in females, respectively. Functional enrichment of DEGs revealed alterations in cholesterol metabolism and mitotic cell cycle regulation in the liver and myeloid leukocyte migration in fat of male offspring, while in female offspring, erythrocyte development and carbohydrate catabolism were affected in fat. Our results demonstrate that exposure to a mixture of legacy and newly emerging PFAS chemicals in adult male mice result in aberrant sperm methylation and altered gene expression of offspring liver and fat in a sex-specific manner. These data indicate that preconception PFAS exposure in males can be transmitted to affect phenotype in the next generation.

A Systematic Review and Meta-analysis on the Impact of Infertility on Men's General Health

CONTEXT

Male infertility has been associated with increased morbidity and mortality.

OBJECTIVE

To perform a systematic review and meta-analysis to provide the most critical evidence on the association between infertility and the risk of incident comorbidities in males.

EVIDENCE ACQUISITION

A systematic review and meta-analysis was performed according to the Meta-analysis of Observational Studies in Epidemiology and Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, and registered on PROSPERO. All published studies on infertile versus fertile men regarding overall mortality and risks of cancer, diabetes, and cardiovascular events were selected from a database search on PubMed, EMBASE, Google Scholar, and Cochrane. Forest plot and quasi-individual patient data meta-analysis were used for pooled analyses. A risk of bias was assessed using the ROBINS-E tool.

EVIDENCE SYNTHESIS

Overall, an increased risk of death from any cause was found for infertile men (hazard risk [HR] 1.37, [95% confidence interval {CI} 1.04-1.81], p = 0.027), and a 30-yr survival probability of 91.0% (95% CI 89.6-92.4%) was found for infertile versus 95.9% (95% CI 95.3-96.4%) for fertile men (p < 0.001). An increased risk emerged of being diagnosed with testis cancer (relative risk [RR] 1.86 [95% CI 1.41-2.45], p < 0.001), melanoma (RR 1.30 [95% CI 1.08-1.56], p = 0.006), and prostate cancer (RR 1.66 [95% CI 1.06-2.61], p < 0.001). As well, an increased risk of diabetes (HR 1.39 [95% CI 1.09-1.71], p = 0.008), with a 30-yr probability of diabetes of 25.0% (95% CI 21.1-26.9%) for infertile versus 17.1% (95% CI 16.1-18.1%) for fertile men (p < 0.001), and an increased risk of cardiovascular events (HR 1.20 [95% CI 1.00-1.44], p = 0.049), with a probability of major cardiovascular events of 13.9% (95% CI 13.3-14.6%) for fertile versus 15.7% (95% CI 14.3-16.9%) for infertile men (p = 0.008), emerged.

CONCLUSIONS

There is statistical evidence that a diagnosis of male infertility is associated with increased risks of death and incident comorbidities. Owing to the overall high risk of bias, results should be interpreted carefully.

PATIENT SUMMARY

Male fertility is a proxy of general men's health and as such should be seen as an opportunity to improve preventive strategies for overall men's health beyond the immediate reproductive goals.

Adult Organophosphate and Carbamate Insecticide Exposure and Sperm Concentration: A Systematic Review and Meta-Analysis of the Epidemiological Evidence

BACKGROUND

Evidence of the negative impacts of contemporary use insecticides on sperm concentration has increased over the last few decades; however, meta-analyses on this topic are rare.

OBJECTIVES

This investigation assessed the qualitative and quantitative strength of epidemiological evidence regarding adult exposure to two classes of contemporary use insecticides-organophosphates (OPs) and N -methyl carbamates (NMCs)-and sperm concentration using robust and reproducible systematic review and meta-analysis methods.

METHODS

Three scientific databases (PubMed, Scopus, and Web of Science), two U.S. government databases (NIOSHTIC-2 and Science.gov), and five nongovernmental organization websites were searched for relevant primary epidemiological studies published in any language through 11 August 2022. Risk of bias and strength of evidence were evaluated according to Navigation Guide systematic review methodology. Bias-adjusted standardized mean difference effect sizes were calculated and pooled using a three-level, multivariate random-effect meta-analysis model with cluster-robust variance estimation.

RESULTS

Across 20 studies, 21 study populations, 42 effect sizes, and 1,774 adult men, the pooled bias-adjusted standardized mean difference in sperm concentration between adult men more- and less-exposed to OP and NMC insecticides was - 0.30 (95% CI: - 0.49 , - 0.10 ; P Satt < 0.01 ). Sensitivity and subgroup analyses explored statistical heterogeneity and validated the model robustness. Although the pooled effect estimate was modified by risk of bias, insecticide class, exposure setting, and recruitment setting, it remained negative in direction across all meta-analyses. The body of evidence was rated to be of moderate quality, with sufficient evidence of an association between higher adult OP and NMC insecticide exposure and lower sperm concentration.

DISCUSSION

This comprehensive investigation found sufficient evidence of an association between higher OP and NMC insecticide exposure and lower sperm concentration in adults. Although additional cohort studies can be beneficial to fill data gaps, the strength of evidence warrants reducing exposure to OP and NMC insecticides now to prevent continued male reproductive harm. https://doi.org/10.1289/EHP12678.

Smoking Induces a Decline in Semen Quality and the Activation of Stress Response Pathways in Sperm

Male infertility is a prevalent concern affecting couples worldwide. While genetic factors, hormonal imbalances, and reproductive system defects play significant roles, emerging evidence suggests that lifestyle choices also profoundly impact male fertility. This study aimed to explore the effects of several lifestyle factors, including tobacco and alcohol consumption, physical activity, and dietary habits, on semen quality parameters and molecular biomarkers. Thirty healthy male volunteers were recruited in the Urology service at Hospital Infante D. Pedro, Aveiro, Portugal. Participants completed lifestyle questionnaires and provided semen samples, which were analyzed according to the World Health Organization criteria by experienced technicians. We also analyzed the expression levels of antioxidant enzymes and heat-shock response-related proteins to explore the activation of signaling pathways involved in stress response within sperm cells. Our results revealed that tobacco consumption reduced semen volume and total sperm count. Although the changes in the percentage of total motility and normal morphology in the smokers' group did not reach statistical significance, a slight decrease was observed. Moreover, we identified for the first time a significant association between tobacco consumption and increased levels of heat shock protein 27 (HSP27) and phosphorylated HSP27 (p-HSP27) in sperm cells, indicating the potential detrimental effects of tobacco on the reproductive system. This study highlights that lifestyle factors reduce semen quality, possibly by inducing stress in sperm, raising awareness about the effects of these risk factors among populations at risk of male infertility.

Male infertility

Clinical infertility is the inability of a couple to conceive after 12 months of trying. Male factors are estimated to contribute to 30-50% of cases of infertility. Infertility or reduced fertility can result from testicular dysfunction, endocrinopathies, lifestyle factors (such as tobacco and obesity), congenital anatomical factors, gonadotoxic exposures and ageing, among others. The evaluation of male infertility includes detailed history taking, focused physical examination and selective laboratory testing, including semen analysis. Treatments include lifestyle optimization, empirical or targeted medical therapy as well as surgical therapies that lead to measurable improvement in fertility. Although male infertility is recognized as a disease with effects on quality of life for both members of the infertile couple, fewer data exist on specific quantification and impact compared with other health-related conditions.

Towards infertility care on equal terms: a prime time for male infertility

Male infertility is a disease that deserves greater clinical attention and research. A universally accepted definition that emphasizes the modulatory impact of age, lifestyle and environmental factors and includes comprehensive diagnostic and treatment guidelines is needed to ensure accurate evaluation and effective care. Accordingly, male infertility should be defined as a disease of the male reproductive system, caused primarily by congenital and genetic conditions, anatomical, endocrine, functional or immunological abnormalities of the reproductive system, genital tract infections, cancer and its related treatments, and sexual disorders incompatible with intercourse. Inadequate lifestyle, exposure to toxicants and advanced paternal age are critical factors acting alone or exacerbating the impact of known causative factors. The focus on male infertility must be balanced with that on female infertility to ensure the best possible outcome for the couple. Fertility clinics are encouraged to prioritize collaboration with reproductive urologists and andrologists to provide the best possible care for male infertility patients.

Unlocking the mystery associated with infertility and prostate cancer: an update

Male-specific reproductive disorders and cancers have increased intensely in recent years, making them a significant public health problem. Prostate cancer (PC) is the most often diagnosed cancer in men and is one of the leading causes of cancer-related mortality. Both genetic and epigenetic modifications contribute to the development and progression of PC, even though the exact underlying processes causing this disease have yet to be identified. Male infertility is also a complex and poorly understood phenomenon believed to afflict a significant portion of the male population. Chromosomal abnormalities, compromised DNA repair systems, and Y chromosome alterations are just a few of the proposed explanations. It is becoming widely accepted that infertility shares a link with PC. Much of the link between infertility and PC is probably attributable to common genetic defects. This article provides an overview of PC and spermatogenic abnormalities. This study also investigates the link between male infertility and PC and uncovers the underlying reasons, risk factors, and biological mechanisms contributing to this association.

A Narrative Review Discussing Vasectomy-Related Impact upon the Status of Oxidative Stress and Inflammation Biomarkers and Semen Microbiota

Background: Male contraceptive approaches besides tubal sterilization involve vasectomy and represent the method of choice among midlife men in developing countries thanks to many advantages. However, the subsidiary consequences of this intervention are insufficiently explored since the involved mechanisms may offer insight into a much more complex picture. Methods: Thus, in this manuscript, we aimed to reunite all available data by searching three separate academic database(s) (PubMed, Web of Knowledge, and Scopus) published in the past two decades by covering the interval 2000–2023 and using a predefined set of keywords and strings involving “oxidative stress” (OS), “inflammation”, and “semen microbiota” in combination with “humans”, “rats”, and “mice”. Results: By following all evidence that fits in the pre-, post-, and vasectomy reversal (VR) stages, we identified a total of n = 210 studies from which only n = 21 were finally included following two procedures of eligibility evaluation. Conclusions: The topic surrounding this intricate landscape has created debate since the current evidence is contradictory, limited, or does not exist. Starting from this consideration, we argue that further research is mandatory to decipher how a vasectomy might disturb homeostasis.

Contaminants of Emerging Concern (CECs) and Male Reproductive Health: Challenging the Future with a Double-Edged Sword

Approximately 9% of couples are infertile, with half of these cases relating to male factors. While many cases of male infertility are associated with genetic and lifestyle factors, approximately 30% of cases are still idiopathic. Contaminants of emerging concern (CECs) denote substances identified in the environment for the first time or detected at low concentrations during water quality analysis. Since CEC production and use have increased in recent decades, CECs are now ubiquitous in surface and groundwater. CECs are increasingly observed in human tissues, and parallel reports indicate that semen quality is continuously declining, supporting the notion that CECs may play a role in infertility. This narrative review focuses on several CECs (including pesticides and pharmaceuticals) detected in the nearshore marine environment of False Bay, Cape Town, South Africa, and deliberates their potential effects on male fertility and the offspring of exposed parents, as well as the use of spermatozoa in toxicological studies. Collective findings report that chronic in vivo exposure to pesticides, including atrazine, simazine, and chlorpyrifos, is likely to be detrimental to the reproduction of many organisms, as well as to sperm performance in vitro. Similarly, exposure to pharmaceuticals such as diclofenac and naproxen impairs sperm motility both in vivo and in vitro. These contaminants are also likely to play a key role in health and disease in offspring sired by parents exposed to CECs. On the other side of the double-edged sword, we propose that due to its sensitivity to environmental conditions, spermatozoa could be used as a bioindicator in eco- and repro-toxicology studies.

Unboxing Industry-Standard AI Models for Male Fertility Prediction with SHAP

Infertility is a social stigma for individuals, and male factors cause approximately 30% of infertility. Despite this, male infertility is underrecognized and underrepresented as a disease. According to the World Health Organization (WHO), changes in lifestyle and environmental factors are the prime reasons for the declining rate of male fertility. Artificial intelligence (AI)/machine learning (ML) models have become an effective solution for early fertility detection. Seven industry-standard ML models are used: support vector machine, random forest (RF), decision tree, logistic regression, naïve bayes, adaboost, and multi-layer perception to detect male fertility. Shapley additive explanations (SHAP) are vital tools that examine the feature's impact on each model's decision making. On these, we perform a comprehensive comparative study to identify good and poor classification models. While dealing with the all-above-mentioned models, the RF model achieves an optimal accuracy and area under curve (AUC) of 90.47% and 99.98%, respectively, by considering five-fold cross-validation (CV) with the balanced dataset. Furthermore, we provide the SHAP explanations of existing models that attain good and poor performance. The findings of this study show that decision making (based on ML models) with SHAP provides thorough explanations for detecting male fertility, as well as a reference for clinicians for further treatment planning.

Reproductive genomics of the mouse: implications for human fertility and infertility

Genetic analyses of mammalian gametogenesis and fertility have the potential to inform about two important and interrelated clinical areas: infertility and contraception. Here, we address the genetics and genomics underlying gamete formation, productivity and function in the context of reproductive success in mammalian systems, primarily mouse and human. Although much is known about the specific genes and proteins required for meiotic processes and sperm function, we know relatively little about other gametic determinants of overall fertility, such as regulation of gamete numbers, duration of gamete production, and gamete selection and function in fertilization. As fertility is not a binary trait, attention is now appropriately focused on the oligogenic, quantitative aspects of reproduction. Multiparent mouse populations, created by complex crossing strategies, exhibit genetic diversity similar to human populations and will be valuable resources for genetic discovery, helping to overcome current limitations to our knowledge of mammalian reproductive genetics. Finally, we discuss how what we know about the genomics of reproduction can ultimately be brought to the clinic, informing our concepts of human fertility and infertility, and improving assisted reproductive technologies.

Male infertility and somatic health - insights into lipid damage as a mechanistic link

Over the past decade, mounting evidence has shown an alarming association between male subfertility and poor somatic health, with substantial evidence supporting the increased incidence of oncological disease, cardiovascular disease, metabolic disorders and autoimmune diseases in men who have previously received a subfertility diagnosis. This paradigm is concerning, but might also provide a novel window for a crucial health reform in which the infertile phenotype could serve as an indication of potential pathological conditions. One of the major limiting factors in this association is the poor understanding of the molecular features that link infertility with comorbidities across the life course. Enzymes involved in the lipid oxidation process might provide novel clues to reconcile the mechanistic basis of infertility with incident pathological conditions. Building research capacity in this area is essential to enhance the early detection of disease states and provide crucial information about the disease risk of offspring conceived through assisted reproduction.

Evolution of the World Health Organization semen analysis manual: where are we?

The WHO (World Health Organization) manuals provide state-of-the-art guidance on how a semen analysis should be carried out. The much anticipated sixth edition of the WHO semen analysis manual has been released 10 years after its previous version and includes essential updates, such as new reference standards for semen volume and microscopic sperm characteristics of recent fathers. A well-conducted semen analysis remains an essential foundation of the infertility evaluation process and affects patient referral, diagnosis and treatment. However, a male infertility work-up primarily based on routine semen analysis does not provide men with an optimal fertility pathway; the primary reasons for routine semen analysis inadequacy in this context include its low predictive value for natural and assisted conception success, its inability to detect sperm DNA and epigenetic deficiencies that might negatively affect embryo development, implantation and offspring well-being, and the substantial overlap between semen parameters of fertile and subfertile individuals. Ideally, a full andrological assessment should be carried out by reproductive urologists in all men dealing with couple infertility and should include a detailed history analysis, physical examination, semen analysis, endocrine assessment and other tests as needed. Only through a complete male infertility work-up will relevant underlying medical and infertility conditions be revealed and potentially treated or alleviated. The ultimate goals of a comprehensive andrological assessment are to positively influence overall male health, pregnancy prospects and offspring well-being.