Lifestyle and semen quality: role of modifiable risk factors

How Food Choices Impact on Male Fertility

PURPOSE OF REVIEW

Increasing evidence on the significance of nutrition in reproduction is emerging from both animal and human studies, suggesting an association between nutrition and male fertility. Here, we have highlighted the impact of the various food groups on reproductive hormones and on spermatogenesis, and the effects of classical and latest dietary patterns such as Mediterranean diet, Western diet, intermittent fasting, ketogenic diet, and vegan/vegetarian diet on male fertility.

RECENT FINDINGS

Nutrients are the precursors of molecules involved in various body's reactions; therefore, their balance is essential to ensure the correct regulation of different systems including the endocrine system. Hormones are strongly influenced by the nutritional status of the individual, and their alteration can lead to dysfunctions or diseases like infertility. In addition, nutrients affect sperm production and spermatogenesis, controlling sexual development, and maintaining secondary sexual characteristics and behaviors. The consumption of fruit, vegetables, fish, processed meats, dairy products, sugars, alcohol, and caffeine importantly impact on male fertility. Among dietary patterns, the Mediterranean diet and the Western diet are most strongly associated with the quality of semen. Nutrients, dietary patterns, and hormonal levels have an impact on male infertility. Therefore, understanding how these factors interact with each other is important for strategies to improve male fertility.

[Male infertility, environment and lifestyle]

BACKGROUND

Since the 1970s, there has been a quantitative and qualitative decline in sperm parameters. The main hypothesis to explain such a rapid evolution is the involvement of environmental and behavioral phenomena.

METHODS

A bibliographic search limited to English and French literature in men published before 7/2023 was carried out on the links between fertility and pollution, xenobiotics, tobacco, narcotics, cannabis, alcohol, weight, sport, sedentary lifestyle, sleep and anabolics.

RESULTS

Profound changes in lifestyle have occurred over the past 50 years: reduced sleep time, sedentary lifestyle, dietary changes, tobacco consumption, use of narcotics and anabolics. These changes have a proven impact on spermogram parameters, and should be corrected in an effort to optimize reproductive health. Other environmental parameters: pollution, exposure to heavy metals, exposure to xenobiotics, phthalates and pesticides… will be more difficult to exclude from patients' daily lives, but deserve to be taken more into account.

CONCLUSION

This review should help the urologist to assess and counsel patients in order to improve their reproductive health. These factors should be routinely investigated in infertile men.

Decline of Sperm Quality over the Last Two Decades in the South of Europe: A Retrospective Study in Infertile Patients

Semen quality has a direct relation to male fertility. Whether sperm variables in humans have decreased over the last years is still uncertain, with some studies showing a decline and others reporting no changes. In this regard, previous research has suggested that lifestyle and environmental conditions may contribute to this variability, calling for regional studies. The present work is a retrospective, unicentric study that includes semen samples analyzed between 1997 and 2017 at the Parc Taulí Hospital (Barcelona metropolitan area). First, a multivariate analysis including the age as a confounding factor showed a statistically significant decrease in semen volume, pH, progressive motility, morphology and total motile sperm over time. Contrarily, no significant variation in sperm count or concentration was observed. Mean reductions per year were -0.02 mL for volume, -0.57% for progressively motile sperm and -0.72% for sperm with normal morphology. Interestingly, the average annual temperature registered by the Spanish Meteorology Agency negatively correlated to sperm morphology and sperm count (Rs = -0.642; p = 0.002 and Rs = -0.435; p = 0.049, respectively). In conclusion, the present study based on infertile patients from the Barcelona area found a decline in sperm motility and morphology, without effects on sperm count. Changes in temperature appeared to be associated to this decline, but further studies are needed to address the mechanisms linked to the observed variations.

Male personal heat exposures and fecundability: A preconception cohort study

BACKGROUND

Several studies indicate adverse effects of selected heat exposures on semen quality, but few studies have directly evaluated fertility as an endpoint.

OBJECTIVE

We evaluated prospectively the association between male heat exposures and fecundability, the per-cycle probability of conception.

MATERIALS AND METHODS

We analyzed data from 3041 couples residing in the United States or Canada who enrolled in a prospective preconception cohort study (2013-2021). At enrollment, males reported on several heat-related exposures, such as use of saunas, hot baths, seat heaters, and tight-fitting underwear. Pregnancy status was updated on female follow-up questionnaires every 8 weeks until conception or a censoring event (initiation of fertility treatment, cessation of pregnancy attempts, withdrawal, loss to follow-up, or 12 cycles), whichever came first. We used proportional probabilities regression models to estimate fecundability ratios (FR) and 95% confidence intervals (CIs) for the association between heat exposures and fecundability, mutually adjusting for heat exposures and other potential confounders.

RESULTS

We observed small inverse associations for hot bath/tub use (≥3 vs. 0 times/month: FR = 0.87, 95% CI: 0.70-1.07) and fever in the 3 months before baseline (FR = 0.94, 95% CI: 0.79-1.12; one cycle of follow-up: FR = 0.84, 95% CI: 0.64-1.11). Little association was found for sauna use, hours of laptop use on one's lap, seat heater use, time spent sitting, and use of tight-fitting underwear. Based on a cumulative heat metric, FRs for 1, 2, 3, and ≥4 versus 0 heat exposures were 0.99 (95% CI: 0.87-1.12), 1.03 (95% CI: 0.89-1.19), 0.94 (95% CI: 0.74-1.19), and 0.77 (95% CI: 0.50-1.17), respectively. Associations were stronger among men aged ≥30 years (≥4 vs. 0 heat exposures: FR = 0.60, 95% CI: 0.34-1.04).

CONCLUSION

Male use of hot tubs/baths and fever showed weak inverse associations with fecundability. Cumulative exposure to multiple heat sources was associated with a moderate reduction in fecundability, particularly among males aged ≥30 years.

Association between tea consumption and semen quality among 1385 healthy Chinese men

Information on the association between tea drinking and semen quality is limited. Little is reported on whether tea drinking is benefit to sperm quality. This cross-sectional and longitudinal study was conducted between April 2017 and July 2018. Participants were healthy men who were screened as potential sperm donors recruited at the Hubei Province Human Sperm Bank of China. A structured questionnaires containing sociodemographic information, daily habits, sperm collection-related information was completed for each participant at interview. Repeated semen samples were taken to examine the sperm parameters, including sperm volume, sperm concentration, sperm count, progressive motility, and total motility. A total of 1385 men with 6466 sperm samples were included in this study. Two groups were compared: tea drinking men (389, 28.1%) and non-tea drinking men (996, 71.9%). Compared with subjects who never drink tea, the analyses showed that sperm concentration and total sperm count were higher in tea-consuming subjects. A 10-year period or more duration of tea drinking significantly increased semen concentrations by 16.27% (P < 0.05). Sperm concentration was increased in subjects with a frequency of tea drinking of 3 days or more per week (P < 0.05) or, among men who were occasional alcohol drinkers, when tea concentration was weak (P < 0.05). No evidence of trend effects (P for trend > 0.05) or interaction effects (P for interaction > 0.05) between tea consumption and sperm quality, respectively. Our findings provide evidence that tea drinking may improve male reproductive health. Long-term, frequent, weak tea drinking tends to increase sperm quality among men with low BMI or health-related behaviors like smoking or alcohol intake.

Study on Influencing Factors of Semen Quality in Fertile Men

Objective

To establish a system for evaluation of semen quality in fertile men by factor analysis (FA).

Methods

The FA method was used to analyze five sperm test indicators for fertile men (sperm pH, sperm motility, sperm progressive motility, semen density, and total sperm number) to determine the evaluation standard of semen quality. Pearson analysis was adopted for correlation testing.

Results

The comprehensive score formula for semen quality of normal fertile men was as follows: comprehensive score of semen quality = (0.38272 F₁ + 0.36359 F₂ + 0.20018 F₃)/94.699. Across the whole fertile population, semen quality was found to be correlated with abstinence period, age of first spermatorrhea, and frequency of intercourse. Smoking, drinking, and place of residence were correlated with semen quality in the high semen quality population. In the population with medium semen quality, only the abstinence period was associated with semen quality.

Conclusion

It is feasible to evaluate the semen quality of fertile men using the FA method. The comprehensive indicators of semen volume, sperm motility, and semen pH can be used as evaluative measures. Across the whole fertile population, the abstinence period and age of first spermatorrhea were correlated with semen quality. In the high semen quality population, smoking and drinking were negatively correlated with semen quality, and participants living in rural areas had better semen quality.

A Factor Analysis Model for Rapid Evaluation of the Semen Quality of Fertile Men in China

Objective

The objective of this study is to reduce the dimension of several indicators with a strong correlation when conducting semen quality analysis in a small number of comprehensive variables that could retain most of the information in the original variables.

Methods

A total of 1132 subjects were recruited from the Maternal and Child Health Institutions of seven provinces in mainland China. They completed the questionnaire and provided semen samples. Visualization of the correlation between variables was realized by using a function chart and correlation in the PerformanceAnalytics package of the R programming language (version 3.6.3 [2020-02-29]). Factor analysis was conducted using the principal function in the psych package of R. Principal component analysis, combined with varimax rotation, was used in the operation of the model, and two common factors were selected and measured to provide values for the common factor. The score coefficient was estimated using the regression method.

Results

The contribution rates of the two common factors to variable X were 43.7% and 33.98%, respectively. When the two common factors were selected, approximately 78% of the information of the original variables could be explained. The correlation coefficients between the first common factor (the quantitative factor) and sperm density, total sperm count, and semen volume were 0.824, 0.984, and 0.544, respectively. The correlation coefficients between the second common factor (the quality factor) and sperm motility and the percentage of forward-moving (progressive spermatozoa) sperm were 0.978 and 0.976, respectively.

Conclusion

The correlation between the original variables of a semen quality analysis was strong and suitable for dimensionality reduction by factor analysis. Factor analysis and dimensionality reduction provide a fast and accurate assessment of semen quality. Patients with low fertility or infertility can be identified and provided with corresponding treatments.

Technological Advancements in Male Infertility Microsurgery

There have been significant advancements in male infertility microsurgery over time, and there continues to be significant promise for new and emerging techniques, technologies, and methodologies. In this review, we discuss the history of male infertility and the evolution of microsurgery, the essential role of education and training in male infertility microsurgery, and new technologies in this space. We also review the potentially important role of artificial intelligence (AI) in male infertility and microsurgery.

Men's perception and understanding of male-factor infertility in the UK

Male-factor infertility is a common but stigmatised issue, and men often do not receive the emotional support and the information they need. This study sought to understand awareness of male fertility issues compared to female fertility among the UK general male public, and also what were perceived as being the optimum methods for providing support for affected men, emotionally and through information. Men feel that male infertility is not discussed by the public as much as female infertility. Lifestyle issues that affect male fertility are not well understood, and men affected by infertility desire more support, including online, from health professionals and through peer support. Health professionals, including those in public health, could offer evidence-based programmes to reduce stigma and increase public knowledge about infertility, as well as offer emotional support to men with infertility problems.

Heat stress response of somatic cells in the testis

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

Phthalate exposure and semen quality in infertile male population from Tianjin, China: Associations and potential mediation by reproductive hormones

Global decline in male fertility and their associations with ubiquitous exposure of phthalates (PAEs) have raised public concerns. However, the current epidemiological data are limited and controversial. Hence, we investigated possible associations between PAE exposure and male infertility. Eleven phthalate metabolites (mPAEs) were determined in urine and serum samples collected from eighty-eight males diagnosed with infertility from Tianjin, China. The median serum levels of mPAE were n.d. -3.63 ng/mL, which were 1-2 orders of magnitude lower than the urinary levels of n.d. -192 ng/mL. Negative associations were identified between urinary follicle-stimulating hormone (FSH) and MiBP and serum MCMHP, as well as testosterone (T) and luteinizing hormone (LH) and the molar concentrations of ∑mPAE, while positive association was found between T and the serum molar concentrations of ∑mDEHP. Positive associations were found between the molar concentrations of serum ∑mPAE and sperm concentration, sperm motility rate, and progressive motility, between mono (2-ethyl-5-carboxypentyl) phthalate (MECPP) and semen volume and total sperm number, and between MCMHP and progressive motility, while negative association was found between mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) and progressive motility. Moreover, FSH was found to mediate the association between serum concentrations of MCMHP and progressive motility (mediation ratio = 41.6%), and LH to mediate the associations between serum concentrations of ∑mPAE and sperm concentration (mediation ratio = 45.7%) and sperm motility rate (mediation ratio = 29.0%). These results also suggested that serum levels of mPAE are a good predictor for male infertility. Further efforts need to be made on toxicological studies to systematically elaborate the internal mechanisms.

Sperm DNA methylation changes after short-term nut supplementation in healthy men consuming a Western-style diet

BACKGROUND

Many environmental and lifestyle factors have been implicated in the decline of sperm quality, with diet being one of the most plausible factors identified in recent years. Moreover, several studies have reported a close association between the alteration of specific sperm DNA methylation signatures and semen quality.

OBJECTIVES

To evaluate the effect of tree nut consumption on sperm DNA methylation patterns in healthy individuals reporting eating a Western-style diet.

MATERIAL AND METHODS

This is a post hoc analysis conducted in a subset of participants (healthy, non-smoking, and young) from the FERTINUTS 14-wk randomized-controlled, parallel trial, recruited between December 2015 and February 2017. The participants included in the current study (n = 72) were randomly selected in a proportion 2:1 from the original FERTINUTS trial between the 98 participants that completed the entire dietary intervention (nut group, n = 48; control group, n = 24). Sperm DNA methylation patterns were examined at baseline and after 14 weeks in 48 individuals consuming 60 g/d of mixed nuts (nut group) and in 24 individuals following the usual Western-style diet avoiding consumption of nuts (control group).

RESULTS

Over the course of the trial, no significant changes in global methylation were observed between groups. However, in the nut group, we identified 36 genomic regions that were significantly differentially methylated between the baseline and the end of the trial and 97.2% of the regions displayed hypermethylation. We identified no such change in the control group over the same period of time. We also utilized the recently developed germ line age calculator to determine if nut consumption resulted in alterations to the epigenetic age of cells and no significant differences were found.

DISCUSSION AND CONCLUSION

Adding nuts to a regular Western-style diet subtly impacts sperm DNA methylation in specific regions, demonstrating that there are some sperm epigenome regions that could respond to diet.

Influence of Lifestyle and Environmental Factors on Semen Quality in Ghanaian Men

Introduction

Male infertility is known to contribute about half of all infertility cases. In Ghana, the prevalence of male infertility is higher (15.8%) than in females (11.8%). Sperm quality is associated with the likelihood of pregnancy and known to be the cause of male fertility problems 90% of the time. Exposure to certain environmental factors reduces semen quality in men. The study examined the effects of environmental and lifestyle factors on semen quality in Ghanaian men.

Materials and Methods

This was a cross-sectional study involving 80 apparent healthy adult males in their reproductive age. Participants were males referred to the laboratory (Immunology Unit of the Korle-Bu Teaching Hospital) for semen analysis test and/or culture and sensitivity. Participants were made to fill out a questionnaire which entailed selected environmental factors (accidents or trauma, exposure to chemicals, radiation, and heat) and lifestyle habits (including alcohol consumption, smoking, and whether participants sat more or less than 4 hours per day). Semen samples were then collected by masturbation into sterile containers and analysed in accordance with WHO guidance for semen analysis within 60 minutes after ejaculation and collection.

Results

About 69% of participants had semen pH within the normal range compared to 15% whose pH were lower than 7.2. There was a significantly high number of immotile sperm cells (p value = 0.017) in participants who sat for more than 4 hours as compared to those that sat for less than 4 hours in a day. Active sperm motility and viability showed significant increase (p value = 0.002 and 0.009, respectively) in participants who kept their cell phones in their side pockets. Smoking produced a twofold decrease in sperm count as smokers had a significantly lower sperm count (12.28 ± 10.95 × 10⁶/ml) compared to the smoke-free (23.85 ± 22.14 × 10⁶/ml). For exposure to STDs, no significant differences were recorded among study groups concerning semen quality.

Conclusion

Sperm quality in Ghanaian men is associated with lifestyle habits. Smoking and sitting for long hours influenced sperm motility and count, respectively. Knowledge of the factors that influence sperm quality in this geographical region can contribute to informed decisions on effective management of infertility in Ghanaian men.

Designing and psychometric of reproductive health related behaviors assessment tool in Iranian males: an exploratory mixed method study protocol

BACKGROUND

Male reproductive health is a relatively new concept, and most men are neglected in reproductive health discussions. Therefore, it appears that there is insufficient information about the male reproductive health. This study aims to design a psychometric instrument for assessing the male reproductive health-related behavior.

METHODS/DESIGN

This is a sequential exploratory mixed-method study with a classical instrument development design. It will be conducted in two qualitative and quantitative phases on the studied units including the men living in Tehran. In the first phase, a qualitative study of a contractual content analysis approach will be conducted in order to perceive the concept of male reproductive health-related behavior, determine the dimensions of the questionnaire, and explore the items. In the second phase, a quantitative study will be carried out to evaluate the psychometric properties as well as (form, content, and construct) validity and reliability of the instrument designed in the first phase. Finally, the instrument will be scored and interpreted.

DISCUSSION

Discovering men's perception of concept of reproductive health-related behavior can help design a valid and reliable questionnaire which can be used in studies evaluating the male reproductive health-related behavior.

ETHICAL CODE

IR.TUMS.FNM.REC.1397.157.

Taking fertility for granted - a qualitative exploration of fertility awareness among young, childless men in Denmark and Sweden

Most previous studies about fertility knowledge and attitudes among men have been based on quantitative methods using questionnaires with fixed-choice response options. The aims of this qualitative study were to explore childless young men's reflections on fertility and infertility through semi-structured interviews. Danish (n = 17) and Swedish (n = 12) young childless men aged between 20 and 30 years in their last year of education were interviewed. Data were analysed using qualitative content analysis. Few informants had considered their own fertility, and most were positive towards fertility treatment. The young men had inadequate knowledge about factors that can potentially impair male and female fertility. On average, the young men each mentioned three different factors they believed influence male and female fertility: (i) health behaviour; (ii) factors beyond personal control; and (iii) age. None mentioned sexual transmitted infections (STIs) but most appeared aware of the effect of increasing age on fertility. The results of this study highlight the need for educational strategies to improve young men's knowledge about fertility and the factors that influence it, particularly about the potential adverse effect of STIs on fertility.

The effect of modifiable lifestyle factors on semen quality

INTRODUCTION AND OBJECTIVES

To examine the association between lifestyle factors (body mass index, smoking, alcohol consumption, coffee intake, physical activity, sauna and cell phone usage, wearing tight-fitting underwear), and conventional semen parameters.

MATERIALS AND METHODS

1311 participants who attended the Andrology Clinic were included in the study. All participants were separated into two groups as men with normozoospermia and dysspermia. All participants answered a questionnaire which contains questions about the modifiable lifestyle factors. The total risk scores were calculated after all the positive lifestyle factors had been counted.

RESULTS

Men with normozoospermia and dysspermia consisted of 852 (65.0%) and 459 (35.0%) participants respectively. A negative relationship between the wearing of tight underwear and having normal semen parameters was detected between the two groups (p=0.004). While going to a sauna regularly was negatively related to semen concentration, wearing tight underwear was also related to both lower motility, normal morphology as well as semen concentration (p<0.05). While the total score of all participants was 5.22±1.34 point, there were no statistical differences between the two groups (p=0.332). It was found that having 3 more or fewer points was not related to any type of semen parameters and results of a spermiogram.

CONCLUSION

The clinicians should give advice to infertile male patients about changing their risky lifestyle, for infertility, to a healthy lifestyle for fertility. Better designed studies, with larger sample sizes using conventional semen analysis with sperm DNA analysis methods, should be planned to identify the possible effects of lifestyle factors on semen quality.

Male exposure to bisphenol A (BPA) and semen quality in the Home Observation of Periconceptional Exposures (HOPE) cohort

BACKGROUND

Exposure to bis-phenol A (BPA) has been associated with reduced semen quality. The objective of this study was to examine associations between BPA measured in serial daily first-morning urine samples and semen quality parameters among men trying to conceive.

METHODS

This prospective, preconception cohort included 161 men ages 18-40 without known subfertility. Men collected daily, first morning urine during their female partner's fertile window. Semen samples were collected through intercourse after the fertile window.

RESULTS

Samples from 161 men were analyzed. Higher geometric mean (GM) BPA exposures (ng/mL) were found among men with abnormal sperm tail morphology (GM = 3.12, 95% CI = 2.43, 4.01) compared to men with normal morphologic findings (GM = 2.39, 95% CI = 2.17, 2.74). There was no association with sperm count.

CONCLUSION

Higher exposure to BPA was associated with abnormal sperm tail morphology in this prospective, pre-conception cohort.

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

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

Effects of folic acid on oligozoospermia with MTHFR polymorphisms in term of seminal parameters, DNA fragmentation, and live birth rate: a double-blind, randomized, placebo-controlled trial

BACKGROUND

It has been reported that paternal folic acid deficiency is correlated with male infertility and increased birth defects in the offspring. However, there are few data concerning the influence of folic acid supplementation on male-factor infertility with MTHFR gene polymorphisms.

OBJECTIVES

To evaluate whether folic acid supplementation has a beneficial effect on oligozoospermia with MTHFR gene polymorphisms in Chinese infertility population.

MATERIALS AND METHODS

The infertile men suffering oligozoospermia with MTHFR gene polymorphisms were randomly divided into the folic acid treatment groups receiving folic acid 0.8 mg daily for 3 months and the placebo groups receiving placebo for 3 months. Semen parameters, seminal MDA, and DNA fragmentation were measured. Furthermore, spontaneous pregnancy rate and live birth rate were evaluated.

RESULTS

Administration of folic acid for 3 months could significantly improve the seminal parameters in patients with MTHFR 677 TT genotype in comparison with that receiving placebo. Moreover, seminal MDA and sperm DNA fragmentation index in patients with MTHFR 677 TT genotype significantly declined at the end of treatment. Spontaneous pregnancy rate and live birth rate tended to be significantly higher in couples in which the men with MTHFR 677 TT genotype receiving folic acid than that receiving placebo. However, folic acid treatment did not exhibit any advantage in MTHFR 677 CT, 1298 AC, 1298 CC, 1793 GA, or combined 677 CT/1298 AC genotype.

DISCUSSION

The anti-oxidation function of folic acid is one of possible mechanisms invovled in improving seminal parameters and pregnancy outcome.

CONCLUSIONS

Folic acid supplementation has a beneficial effect on oligozoospermia with MTHFR 677 TT genotype in term of seminal parameters, seminal MDA, sperm DNA fragmentation, and pregnancy outcome.

Impact of physical activity on semen quality among men from infertile couples

OBJECTIVE

To determine the implication of general physical activity and some specific sports in semen quality in men from infertile couples.

STUDY DESIGN

This is an observational study performed in men from infertile couples (n = 454). The interventions performed involved analyzing semen quality parameters according to 2010 WHO criteria and assessing physical activity by means of an International Physical Activity Questionnaire.

RESULT(S)

There was no association between different levels of general physical activity and semen parameters. We neither found association with running, cycling and racquet sports. Interestingly, people who practice weightlifting more than two hours per week presented significantly lower sperm concentration (linear coefficient = -24.80) and lower total sperm count (linear coefficient = -70.87) in comparison with participants that did not practice regular exercise.

CONCLUSION(S)

From a reproductive point of view, there does not seem to be any reason to recommend the increase or the decrease in general physical activity in males from infertile couples. However, additional studies are needed to investigate the relationship between weightlifting and sperm quality.

Adherence to the Mediterranean diet is positively associated with sperm motility: A cross-sectional analysis

The aim of this cross-sectional analysis is to investigate the associations between the adherence to the Mediterranean Diet (MD) and semen quality parameters. To assess the adherence to the MD, the Trichopoulou score was used. Semen parameters were assessed as described in the 2010 WHO’s report and the results are showed across tertiles of MD adherence. A total of 106 participants were included. Compared to those in the lowest MD adherence tertile, participants in the top tertile had statistically significant higher BMI and waist circumference and consumed more energy, and also had statistically significant higher semen pH, and total sperm motility and progressive sperm motility percentages, and lower sperm immotility percentages. Moreover, percentage of total and progressive motility were significantly higher among those subjects in the higher adherence to MD in comparison with those in low-medium adherence category. The multivariable linear regression models evaluating the relationship between the sperm quality parameters and tertiles of MD adherence adjusted by age, energy and BMI showed that compared with the lowest tertile, men in the highest tertile had a higher percentage of total sperm motility [β non-standardized coefficient = 12.785]. These findings suggest that adherence to the MD was positively associated with sperm motility.

Molecular Mechanisms and Signaling Pathways Involved in Sertoli Cell Proliferation

Sertoli cells are somatic cells present in seminiferous tubules which have essential roles in regulating spermatogenesis. Considering that each Sertoli cell is able to support a limited number of germ cells, the final number of Sertoli cells reached during the proliferative period determines sperm production capacity. Only immature Sertoli cells, which have not established the blood-testis barrier, proliferate. A number of hormonal cues regulate Sertoli cell proliferation. Among them, FSH, the insulin family of growth factors, activin, and cytokines action must be highlighted. It has been demonstrated that cAMP/PKA, ERK1/2, PI3K/Akt, and mTORC1/p70SK6 pathways are the main signal transduction pathways involved in Sertoli cell proliferation. Additionally, c-Myc and hypoxia inducible factor are transcription factors which participate in the induction by FSH of various genes of relevance in cell cycle progression. Cessation of proliferation is a pre-requisite to Sertoli cell maturation accompanied by the establishment of the blood-testis barrier. With respect to this barrier, the participation of androgens, estrogens, thyroid hormones, retinoic acid and opioids has been reported. Additionally, two central enzymes that are involved in sensing cell energy status have been associated with the suppression of Sertoli cell proliferation, namely AMPK and Sirtuin 1 (SIRT1). Among the molecular mechanisms involved in the cessation of proliferation and in the maturation of Sertoli cells, it is worth mentioning the up-regulation of the cell cycle inhibitors p21Cip1, p27Kip, and p19INK4, and of the gap junction protein connexin 43. A decrease in Sertoli cell proliferation due to administration of certain therapeutic drugs and exposure to xenobiotic agents before puberty has been experimentally demonstrated. This review focuses on the hormones, locally produced factors, signal transduction pathways, and molecular mechanisms controlling Sertoli cell proliferation and maturation. The comprehension of how the final number of Sertoli cells in adulthood is established constitutes a pre-requisite to understand the underlying causes responsible for the progressive decrease in sperm production that has been observed during the last 50 years in humans.

Human Semen Quality, Sperm DNA Damage, and the Level of Urinary Concentrations of 1N and TCPY, the Biomarkers of Nonpersistent Insecticides

The aim of the study was to evaluate the association between environmental exposure to nonpersistent insecticides and semen quality (concentration, motility, morphology, computer-aided semen analysis [CASA] parameters, and sperm DNA damage). Urine samples (n = 315) collected from men who attended the infertility clinic with normal semen concentration of 15 to 300 mln/ml and age under 45 years were analyzed for two metabolites (1-naphthol [1N] and 3,5,6-trichloro-2-pyridinol [TCPY]) of nonpersistent insecticides. Participants provided semen, blood, and saliva samples; additionally, men filled a detailed questionnaire. The results identified that urinary TCPY concentration was significantly associated with a decrease in motility; also there was a positive association between TCPY and DNA fragmentation index (DFI). 1N concentration was negatively associated with a percentage of sperm with normal morphology and positively with one of the CASA parameters (curvilinear velocity [VCL]). The results suggest that environmental exposure to nonpersistent insecticides may have an impact on semen quality parameters and sperm DNA damage.

Effect of nut consumption on semen quality and functionality in healthy men consuming a Western-style diet: a randomized controlled trial

Background

Human semen quality has declined in industrialized countries. Pollution, smoking, and the consumption of a Western-style diet are all hypothesized as potential causes.

Objective

We evaluated the effect of chronic consumption of nuts on changes in conventional semen parameters and the potential mechanisms implicated.

Design

The FERTINUTS study was a 14-wk randomized, controlled, parallel trial. A total of 119 healthy men, aged 18-35 y, were allocated to 1 of 2 intervention groups: one group was fed the usual Western-style diet enriched with 60 g of a mixture of nuts/d (nut group), and the other was fed the usual Western-style diet avoiding nuts (control group). Semen and blood samples were collected at baseline and at the end of the intervention. Dietary information was recorded throughout the trial. Changes in conventional semen parameters (pH, volume, sperm count and concentration, motility, and morphology) were determined as primary outcomes. The effect of nut consumption on sperm DNA fragmentation (SDF), reactive oxygen species (ROS) production, chromosome anomalies (X, Y, and 18), total DNA methylation, and microRNA expression were measured in sperm samples as potential causes of the changes in the seminogram.

Results

Compared with the control group, improvements in total sperm count (P = 0.002) and vitality (P = 0.003), total motility (P = 0.006), progressive motility (P = 0.036), and morphology of sperm (P = 0.008) were observed in the nut group. Participants in the nut group showed an increase in the consumption of total fat, monounsaturated fatty acids, polyunsaturated fatty acids, magnesium, vitamin E, α-linolenic acid, total omega-3 (n-3) and ω-3:ω-6 ratio intake during the intervention. Participants in the nut group showed a significant reduction in SDF (P < 0.001) and in the expression of hsa-miR-34b-3p (P = 0.036). No significant changes in ROS, sperm chromosome anomalies, or DNA methylation were observed between groups.

Conclusions

The inclusion of nuts in a Western-style diet significantly improves the total sperm count and the vitality, motility, and morphology of the sperm. These findings could be partly explained by a reduction in the sperm DNA fragmentation. This trial was registered at ISRCTN as ISRCTN12857940.

Urinary Bisphenol A Levels and Male Fertility

Bisphenol A (BPA) is a high-production volume industrial chemical found in many consumer products. BPA is a suspected potent endocrine disruptor, with endocrine-disrupting properties demonstrated in animal studies. Few human studies have examined bisphenol A exposure in relation to male fertility and, results are divergent. The aim of the study is to examine the associations between urinary BPA concentration and male fertility. Bisphenol A urinary concentrations were measured using gas chromatography coupled with tandem mass spectrometry in 315 men under 45 years of age with normal sperm concentration (⩾15 mln/ml) recruited from a male reproductive health clinic. Participants were interviewed and provided a semen sample. BPA was detected in 98.10% of urine samples, with a median concentration of 1.87 µg/l (1.63 µg/ g creatinine). A multiple linear regression analysis identified a positive association between the urinary concentrations of bisphenol A 25th–50th percentile and total sperm sex chromosome disomy (p = .004). Also when modeled as continuous variable urinary BPA concentration increased total sperm sex chromosome disomy (p = .01). Urinary concentration of BPA also increase the percentage of immature sperm (HDS) (p = .018) and decrease motility (p = .03). The study provides evidence that exposure to BPA is associated with poorer semen quality. Future studies are needed to confirm these findings.

Type of underwear worn and markers of testicular function among men attending a fertility center

STUDY QUESTION

Is self-reported type of underwear worn associated with markers of testicular function among men at a fertility center?

SUMMARY ANSWER

Men who reported most frequently wearing boxers had higher sperm concentration and total count, and lower FSH levels, compared to men who did not.

WHAT IS KNOWN ALREADY

Elevated scrotal temperatures are known to adversely affect testicular function. However, the epidemiologic literature on type of underwear, as a proxy of scrotal temperature, and male testicular function is inconsistent.

STUDY DESIGN, SIZE, DURATION

This is a cross-sectional study including 656 male partners of couples seeking infertility treatment at a fertility center (2000-2017).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Self-reported information on type of underwear worn was collected from a take-home questionnaire. Semen samples were analyzed following World Health Organization guidelines. Enzyme immunoassays were used to assess reproductive hormone levels and neutral comet assays for sperm DNA damage. We fit linear regression models to evaluate the association between underwear type and testicular function, adjusting for covariates and accounting for multiple semen samples.

MAIN RESULTS AND THE ROLE OF CHANCE

Men had a median (interquartile range) age of 35.5 (32.0, 39.3) years and BMI of 26.3 (24.4, 29.9) kg/m2. About half of the men (53%; n = 345) reported usually wearing boxers. Men who reported primarily wearing boxers had a 25% higher sperm concentration (95% CI = 7, 31%), 17% higher total count (95% CI = 0, 28%) and 14% lower serum FSH levels (95% CI = -27, -1%) than men who reported not primarily wearing boxers. Sperm concentration and total count were inversely related to serum FSH. Furthermore, the differences in sperm concentration and total count according to type of underwear were attenuated after adjustment for serum FSH. No associations with other measured reproductive outcomes were observed.

LIMITATIONS, REASONS FOR CAUTION

Our results may not be generalizable to men from the general population. Underwear use was self-reported in a questionnaire and there may be misclassification of the exposure. The cross-sectional design limits causal inference, and residual confounding is still possible owing to lack of information on other modifiable life styles that can also modify scrotal heat (e.g. type of trousers worn, textile fabric of the underwear). Blood sampling was not limited to the morning and, as a result, we may have missed associations with testosterone or other hormones with significant circadian variation despite statistical adjustment for time of blood draw.

WIDER IMPLICATIONS OF THE FINDINGS

Certain styles of male underwear may impair spermatogenesis and this may result in a compensatory increase in gonadotrophin secretion, as reflected by higher serum FSH levels among men who reported most frequently wearing tight underwear. Confirmation of these findings, and in particular the findings on FSH levels suggesting a compensatory mechanism, is warranted.

STUDY FUNDING/COMPETING INTEREST(S)

The project was financed by Grants (R01ES022955, R01ES009718, P30ES000002, and K99ES026648) from the National Institutes of Health. None of the authors has any conflicts of interest to declare.

Fit to father? Online accounts of lifestyle changes and help-seeking on a male infertility board

The reproductive realm is routinely viewed as a feminised space requiring women's commitment and labour. By contrast, men's procreative contributions and 'reproductive masculinity' is represented as unproblematic, with men assumed to be fertile across the lifespan. Recent scientific research has, however, cast doubt over these longstanding assumptions, suggesting that a link does exist between 'lifestyle' factors and male fertility. The notion that fertility can be improved with effort (for both women and men) can be located within wider cultural and political shifts which construct individuals as increasingly responsible for acting on health messages and engaging in self-disciplining body projects. Through an exploration of 'lifestyle changes' within a men's online infertility discussion forum board, this paper examines how discourses of individualisation healthism and masculinity are reproduced and interlinked. Our thematic analysis indicates that 'lifestyle work' is construed as crucial for achieving conception - and as a means to demonstrate men's commitment to the dyadic goal of parenthood, which in turn may challenge and extend previous notions of 'reproductive masculinity'.

Environmental levels of triclosan and male fertility

Triclosan is a synthetic chemical with broad antimicrobial activity that has been used extensively in consumer products, including personal care products, textiles, and plastic kitchenware, although the exposure which is widespread evidence from human studies is scarce. Our study aims to investigate the relationship between triclosan exposure and male fertility. Triclosan (TCS) urinary concentrations were measured using gas chromatography coupled with tandem mass spectrometry in 315 men recruited from a male reproductive health clinic with normal sperm concentration (≥ 15 mln/ml) (WHO 2010) under 45 years of age. Participants were interviewed and provided a semen sample. TCS was detected in 84.13% of urine samples, with a median concentration of 2.83 μg/l (2.57 μg/g creatinine). A multiple linear regression analysis showed a positive association between the urinary concentrations of triclosan 50th-75th percentile and ≥ 50 percentile and percentage of sperm with abnormal morphology (p = 0.016 and p = 0.002, respectively). The study provides evidence that exposure to triclosan is associated with poorer semen quality. Future studies are needed to confirm these findings.

Air Pollution and Human Sperm Sex Ratio

The present study was designed to address the hypothesis that exposure to specific air pollutants may impact human sperm Y:X chromosome ratio. The study population consisted of 195 men who were attending an infertility clinic for diagnostic purposes and who had normal semen concentration of 15–300 mln/ml (WHO, 2010). Participants represented a subset of men in a multicenter parent study conducted in Poland to evaluate environmental factors and male fertility. Participants were interviewed and provided a semen sample. The Y:X ratio was assessed by fluorescent in situ hybridization (FISH). Air quality data were obtained from the AirBase database. In multivariate analysis the significant reduction was observed in the proportion of Y/X chromosome bearing sperm and exposure to particulate matter >10 μm in aerodynamic diameter PM₁₀ (p = .009) and particulate matter <10 μm in aerodynamic diameter PM_2.5 (p = .023). The observed effects of a lower Y:X sperm chromosome ratio among men exposed to air pollution support the evidence that the trend of declining sex ratio in several societies over past decades has been due to exposure to air pollution; however due to limited data on this issue, the obtained results should be confirmed in longitudinal studies.

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

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

Environmental exposure to parabens and sperm chromosome disomy

Parabens are widely used as antimicrobial preservatives in cosmetics, pharmaceuticals, food and beverage processing due to their board spectrum of activity, inertness, and low cost. The study population consisted of 156 men under 45 years of age who attended the infertility clinic for diagnostic purposes with normal semen concentration of 15-300 mln/ml. Participants were interviewed and provided a semen sample. The parabens concentrations: ethyl paraben (EP), butyl paraben (BP), methyl paraben (MP), and iso-butyl paraben (iBuP) were analyzed in the urine using a validated gas chromatography ion-tap mass spectrometry method. The positive association was found between urinary level of BP and XY18 disomy (p = 0.045) and PP and disomy of chromosome 13 (p = 0.007). This is the first study to examine these relationships, and replication of our findings is needed before the association between parabens concentration in urine and aneuploidy can be fully defined. These findings may be of concern due to increased parabens use.

Physically Active Men Show Better Semen Parameters than Their Sedentary Counterparts

Background

The quality of semen depends upon several factors such as environment, life style, physical activity, age, and occupation. The aim of this study was to analyze and compare the conventional and functional semen parameters in men practicing vigorous physical activity to those of sedentary men.

Materials and Methods

In this descriptive cross-sectional study, semen samples of 17 physically active men and 15 sedentary men were collected for analysis. Semen analysis was performed according to the World Health Organization (WHO) guidelines, while functional parameters were evaluated by flow cytometry.

Results

Results showed that several semen parameters (semen volume, viability, progressive motility, total motility, normal morphology, and moribund cells) were superior in the physically active group in comparison with the sedentary group. Semen parameters such as viability, progressive motility and total motility, as well as the percentage of moribund spermatozoa were significantly different between both groups. However, sperm DNA damage, lipid peroxidation and mitochondrial potential were not significantly different among the groups.

Conclusion

Nevertheless, the physical activity shows better semen parameters than sedentary group. Taken together, our results demonstrate that regular physical activity has beneficial impact in sperm fertility parameters and such a life style can enhance the fertility status of men.

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

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

The need to improve fertility awareness

Women and men globally are delaying the birth of their first child. In the UK, the average age of first conception in women is 29 years. Women experience age-related fertility decline so it is important that men and women are well-informed about this, and other aspects of fertility. A group of UK stakeholders have established the Fertility Education Initiative to develop tools and information for children, adults, teachers, parents and healthcare professionals dedicated to improving knowledge of fertility and reproductive health.

Exposure to widespread environmental endocrine disrupting chemicals and human sperm sex ratio

In recent years, a trend toward a declining proportion of male births has been noted in several, but not all, industrialized countries. The underlying reason for the drop in the sex ratio is unclear, but one theory states that widespread environmental endocrine disrupting chemicals affecting the male reproductive system in a negative manner could be part of the explanation. The present study was designed to investigate whether the urinary phthalate, pyrethroids and polycyclic aromatic hydrocarbons metabolites concentrations were associated with sperm Y:X ratio. The study population consisted of 194 men aged under 45 years of age who attended infertility clinic in Lodz, Poland for diagnostic purposes with normal semen concentration of 20-300 mln/ml or with slight oligozoospermia (semen concentration of 15-20 mln/ml) (WHO, 1999). The Y:X ratio was assessed by fluorescent in situ hybridization. Urinary concentrations of 1-hydroxypyrene were measured by high performance liquid chromatography, phthalate metabolites were analyzed using a procedure based on the LC-MS/MS methods and metabolites of synthetic pyrethroids were assessed by gas chromatography ion-tap mass spectrometry method. After adjustment for potential confounders (past diseases, age, abstinence, smoking, alcohol consumption, sperm concentration, motility, morphology) 5OH MEHP, CDCCA to TDCCA and 1-OHP was negatively related to Y:X sperm chromosome ratio (p = 0.033, p < 0.001, p = 0.047 respectively). As this is the first study to elucidate the association between the level of metabolites of widespread environmental endocrine disrupting chemicals (phthalates, synthetic pyrethroids, polycyclic aromatic hydrocarbons) on sex chromosome ratio in sperm therefore, these findings require further replication in other populations.

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

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

Effects of cell phone use on semen parameters: Results from the MARHCS cohort study in Chongqing, China

Epidemiological and experimental evidence for detrimental effects of cell phone use on semen quality is still equivocal. And that recruiting participants from infertility clinic not from general population may raise the possibility of a selection bias. To investigate effects of cell phone use on semen parameters in a general population,We screened and documented the cell phone use information of 794 young men from the Male Reproductive Health in Chongqing College students (MARHCS) cohort study in 2013, followed by 666 and 568 in 2014 and 2015, respectively. In the univariate regression analyses, we found that the daily duration of talking on the cell phone was significantly associated with decreased semen parameters, including sperm concentration [β coefficient=-6.32% per unit daily duration of talking on the cell phone (h); 95% confidence interval (CI), -11.94, -0.34] and total sperm count (-8.23; 95% CI, -14.38, -1.63) in 2013; semen volume (-8.37; 95% CI, -15.93, -0.13) and total sperm count (-16.59; 95% CI, -29.91, -0.73) in 2015]. Internet use via cellular networks was also associated with decreased sperm concentration and total sperm counts in 2013 and decreased semen volume in 2015. Multivariate analyses were used to adjust for the effects of potential confounders, and significant negative associations between internet use and semen parameters remained. Consistent but nonsignificant negative associations between talking on the cell phone and semen parameters persisted throughout the three study years, and the negative association was statistically significant in a mixed model that considered all three years of data on talking on the cell phone and semen quality. Our results showed that certain aspects of cell phone use may negatively affect sperm quality in men by decreasing the semen volume, sperm concentration, or sperm count, thus impairing male fertility.

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

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

Choice of underwear and male fecundity in a preconception cohort of couples

Our objective was to investigate the relationship between male underwear-type worn during daytime/bedtime and male fecundity as measured by semen quality and time-to-pregnancy. We used data from a prospective preconception cohort conducted in 16 counties in Michigan and Texas, USA. 501 couples were enrolled and followed for 12 months of trying, which facilitated capture of time-to-pregnancy (in cycles), 6-cycle conception delay, and 12-month infertility. Male partners provided semen samples via in-home collection for next-day semen analysis comprised of 35 semen quality endpoints. At enrollment, men provided information on type of underwear worn during daytime and bedtime and were classified into 6 categories by underwear choice (n = 491): (i) briefs day/night, (ii) boxer-briefs day/night, (iii) boxers day/night, (iv) briefs day and boxers/none at night, (v) boxer-briefs day and boxers/none at night, (vi) boxers day and none at night. 473 (96%) men had semen analysis performed. Men switching from their usual daytime underwear to boxers/none for bed (groups 4, 5, 6) had the most evidence of change in semen quality endpoints (10 of 11 differences) relative to men wearing briefs day/night (group 1). Group 4 men had lower percent of sperm with coiled tail (β = -0.18, 95% CI: -0.35, -0.01), higher percent round (β = 0.22, 95% CI: 0.01, 0.42), number of immature sperm (β = 0.44, 95% CI: 0.11, 0.77), and amplitude head displacement (β = 0.57, 95% CI: 0.10, 1.03). Group 5 men had higher sperm head perimeter (β=0.17, 95% CI: 0.002, 0.34), amplitude head displacement (β = 0.47, 95% CI: 0.03, 0.91), percent cytoplasmic droplet (β = 0.44, 95% CI: 0.11, 0.77) and high DNA stainability (β=0.39, 95% CI: 0.01, 0.78). After false discovery rate control, no differences remained significant. No significant differences in time-to-pregnancy, conception delay, or infertility were observed. In summary, male underwear choice is associated with few differences in semen parameters; no association with time-to-pregnancy is observed providing reassurance to couples attempting pregnancy.

Environmental Exposure to Triclosan and Semen Quality

Triclosan (2,4,4′-trichloro-2′-hydroxy-diphenyl ether, TCS) is widely used in personal care, household, veterinary and industrial products. It was considered as a potential male reproductive toxicant in previous in vitro and in vivo studies. However, evidence from human studies is scarce. Our study aims to investigate the relationship between TCS exposure and semen quality. We measured urinary TCS concentrations in 471 men recruited from a male reproductive health clinic. TCS was detected in 96.7% of urine samples, with a median concentration of 0.97 ng (mg·creatinine)⁻¹ (interquartile range, 0.41–2.95 ng (mg·creatinine)⁻¹). A multiple linear regression analysis showed a negative association between natural logarithm (Ln) transformed TCS concentration (Ln-TCS) and Ln transformed number of forward moving sperms (adjusted coefficient β = −0.17; 95% confidence interval (CI) (−0.32, −0.02). Furthermore, among those with the lowest tertile of TCS level, Ln-TCS was negatively associated with the number of forward moving sperms (β = −0.35; 95% CI (−0.68, −0.03)), percentage of sperms with normal morphology (β = −1.64; 95% CI (−3.05, −0.23)), as well as number of normal morphological sperms, sperm concentration and count. Our findings suggest that the adverse effect of TCS on semen quality is modest at the environment-relevant dose in humans. Further studies are needed to confirm our findings.