The impact of metabolically healthy obesity in primary infertile men: Results from a cross-sectional study

Association of lifestyle and occupational exposure factors with human semen quality: a cross-sectional study of 1060 participants

The incidence of male infertility (MI) is rising annually. However, the lifestyle and occupational exposure factors contributing to MI remain incompletely understood. This study explored the effects of self-reported lifestyle and occupational exposure factors on semen quality. Among 1060 subjects invited to participate, 826 were eligible. The participants' general characteristics, lifestyle, and occupational exposure factors were collected immediately before or after semen evaluation through an online questionnaire. Initially, univariate analysis was used to investigate the relationship between the abovementioned factors and semen quality. The results indicated significant associations between low semen quality and various factors, including age, BMI, infertility type and duration, abstinence time, semen and sperm parameters, smoking, alcohol consumption, irregular sleep habits, and frequent exposure to high temperatures and chemicals at work (p < 0.05). Then, multivariate analysis was conducted to identify factors independently associated with low semen quality. Adjustment for relevant confounders was achieved by including factors with a p-value < 0.25 from univariate analyses as covariates in the binomial and ordered logistic regression models. The results suggested that alcohol consumption was a positive factor for sperm concentration (odds ratio [OR] = 0.60; 95% confidence interval [CI] = 0.36-0.99; p = 0.045). The groups with a BMI ≥ 24 and <28 kg/m2 showed a significant decrease in sperm progressive motility when compared to the reference group (BMI < 24 kg/m2) (OR = 0.63; 95% CI = 0.46-0.87, p = 0.005). In addition, the groups that drank green tea <1 time/week (OR = 1.52, 95% CI = 1.05-2.2) and 1-4 times/week (OR = 1.61, 95% CI = 1.02-2.54) exhibited significantly increased sperm DFI values compared with the group that drank green tea 5-7 times/week. In conclusion, these findings underscore the importance of maintaining a normal weight and regularly consuming green tea for men.

One out of two idiopathic infertile men has pathologic sperm DNA fragmentation values: Potential implications for clinical practice

OBJECTIVES

To investigate the distribution of sperm DNA fragmentation (SDF) values and their association with clinical and seminal parameters in idiopathic infertile men.

DESIGN, PATIENTS, MEASUREMENTS

Data from 3224 primary infertile men (belonging to couples having failed to conceive a pregnancy within 12 months) who underwent a thorough diagnostic work-up were analysed. A SDF value ≥ 30% (according to Sperm Chromatin Structure Assay) was considered pathologic. We excluded: (1) men with genetic abnormalities; (2) men with history of cryptorchidism; (3) men with biochemical hypogonadism; (4) men with clinical varicocele; and (5) men with other possible known aetiological factors. Descriptive statistics and logistic regression analyses were used to describe the whole cohort.

RESULTS

Of all, 792 (23%) men with at least one abnormal WHO semen parameter but without any identified aetiologic factor for infertility, were considered as idiopathic infertile men. Of 792, 418 (52.7%) men had SDF ≥30%. Men with pathologic SDF were older (p = .02), had higher Follicle-stimulating hormone (FSH) (p = .04) but lower total testosterone (p = .03) values than those with SDF <30%. The homoeostatic model assessment index for insulin resistance (HOMA-IR) was higher in men with SDF ≥30% (p = .01). Idiopathic infertile men with SDF ≥30% presented with lower sperm concentration (p < .001) and lower progressive sperm motility (p < .01) than those with SDF < 30%. Logistic regression analysis revealed that older age (OR: 1.1, p = .02) and higher HOMA-IR score (OR: 1.8, p = .03) were associated with SDF ≥ 30%, after accounting for FSH and sperm concentration values.

CONCLUSIONS

Approximately half of infertile men categorized as idiopathic had pathologic SDF values. Idiopathic infertile men with pathologic SDF showed worse clinical, hormonal and semen parameters than those with normal SDF values. These results suggest that including SDF testing could be clinically relevant over the real-life management work-up of infertile men.

Contemporary Diagnostic Work-Up for Male Infertility: Emphasizing Comprehensive Baseline Assessment

Infertility is a prevalent issue affecting many couples during their reproductive years, with a significant number facing challenges in conceiving despite regular unprotected intercourse. Male factor infertility (MFI) contributes significantly to these cases, with a significant proportion of men lacking an identifiable etiology. As such, a thorough assessment of MFI has become increasingly vital for personalized management. This position paper from the Andrology team at IRCCS Ospedale San Raffaele emphasizes a comprehensive and individualized approach to MFI work-up, addressing the evolving challenges encountered in clinical practice. Our approach involves a thorough diagnostic work-up to identify the underlying causes of MFI, integrating insights from extensive literature review and our proprietary data. Our data demonstrates that an extensive diagnostic assessment allows us to identify at least one underlying cause of MFI in most infertile men. However, challenges persist in diagnosing less severe phenotypes with unclear etiology. We discuss the importance of individualized MFI work-up and its implications for developing rational therapeutic protocols. Lastly, this paper highlights the necessity for a personalized diagnostic assessment, addressing the daily clinical challenges and emphasizing tailored approaches to try to improve outcomes among couples seeking first medical help for infertility.

Impact of metabolic syndrome factors on sperm DNA fragmentation in males from infertile couples: A systematic review and meta-analysis

PURPOSE

To investigate the impact of metabolic syndrome factors on sperm DNA fragmentation (sDF) in males from infertile couples.

METHODS

A systematic literature search was performed across ten databases for literature published from January 1, 2013 until September 13, 2023. The protocol has been registered on PROSPERO (CRD42023458359), and the literature search strategy is adhered to the PRISMA framework. Studies that evaluated sDF, as indicated by DNA fragmentation index (%DFI), in males from infertile couples in relation to metabolic syndrome factors were included. Meta-analysis, using random effects model and Bayesian framework network, was performed, and data were presented as Standardized Mean Differences (SMD) with corresponding 95 % Confidence Interval (CI).

RESULTS

Of the 2579 citations identified, eleven studies were included in this meta-analysis. The findings revealed that the %DFI was not associated with overall metabolic syndrome factors (p-tot = 0.235; SMD = 0.57 [95 %CI: -0.37, 1.52]), metabolic syndrome status (p-tot = 0.337; SMD = 0.08 [95 %CI: -0.08, 0.24), increased body mass index (p-tot = 0.237; SMD = 0.71 [95 %CI: -0.47, 1.89]), or glycaemic profile (p-tot = 0.93; SMD = 0.13 [95 %CI: -2.72, 2.98]). High levels of heterogeneity were observed (p < 0.01) in all subgroups, except for metabolic syndrome status.

CONCLUSION

The association between metabolic syndrome factors and sDF is conflicting. However, interpreting the association requires caution, as confounding factors, indicated by high heterogeneity, may conceal the outcome. Metabolic syndrome may influence other factors contributing to male infertility, highlighting the importance of promoting a healthy lifestyle.

Low Birth Weight is Associated with Sperm DNA Fragmentation and Assisted Reproductive Technology Outcomes in Primary Infertile Men: Results of a Cross-Sectional Study

PURPOSE

To assess the relationship between clinical and semen characteristics and assisted reproductive technology (ART) outcomes with different birth weight (BW) categories in a cohort of infertile men.

MATERIALS AND METHODS

Data from 1,063 infertile men were analyzed. Patients with BW ≤2,500, 2,500-4,000, and ≥4,000 g were considered as having low BW (LBW), normal BW (NBW), and high BW (HBW), respectively. Testicular volume (TV) was assessed with a Prader orchidometer. Serum hormones were measured in all cases. Semen analyses were categorized based on 2021 World Health Organization reference criteria. Sperm DNA fragmentation (SDF) was tested in every patient and considered pathological for SDF >30%. ART outcomes were available for 282 (26.5%) patients. Descriptive statistics and logistic regression analyses detailed the association between semen parameters and clinical characteristics and the defined BW categories.

RESULTS

Of all, LBW, NBW, and HBW categories were found in 79 (7.5%), 807 (76.0%), and 177 (16.5%) men, respectively. LBW men had smaller TV, presented higher follicle-stimulating hormone (FSH) but lower total testosterone levels compared to other groups (all p<0.01). Sperm progressive motility (p=0.01) and normal morphology (p<0.01) were lower and SDF values were higher (all p<0.01) in LBW compared to other groups. ART pregnancy outcomes were lower in LBW compared to both NBW and HBW categories (26.1% vs. 34.5% vs. 34.5%, p=0.01). At multivariable logistic regression analysis, LBW was associated with SDF >30% (odd ratio [OR] 3.7; p<0.001), after accounting for age, Charlson Comorbidity Index (CCI), FSH, and TV. Similarly, LBW (OR 2.2; p<0.001), SDF >30% (OR 2.9; p<0.001) and partner's age (OR 1.3; p=0.001) were associated with negative ART outcomes, after accounting for the same predictors.

CONCLUSIONS

LBW was associated with impaired clinical and semen characteristics in infertile men compared to both NBW and HBW. SDF and ART outcomes were significantly worse in the LBW group.

Observational Cross-Sectional Study on Mediterranean Diet and Sperm Parameters

Infertility, affecting 15 to 25% of couples in the most developed countries, is recognized by the World Health Organization as a public health issue at a global level. Different causes are acknowledged to reduce fertility in both sexes. In particular, about 40-50% of cases recognize a male factor. Dietary habits and lifestyle are acknowledged to influence sperm quality and are therefore important modifiable factors in male reproductive health. Conditions such as overweight/obesity, impaired glucose metabolism and determinants of metabolic syndrome, together with unhealthy lifestyle behavior, i.e., smoking cigarettes and physical inactivity, are suggested to have a negative impact on male fertility. While individual elements and characteristics of the Western diet and habits are considered risk factors for male infertility, the Mediterranean diet (MD) seems to promote reproductive potential for improving sperm quality. It is also interesting to note that previous observational studies reported a positive correlation between the consumption of the single food classes of the MD pattern (i.e., vegetables and fruits, poultry, fish and seafood, whole grains, low-fat dairy products) and the quality of several sperm parameters. To evaluate the relationship between sperm parameters and MD adherence, we performed a cross-sectional study on the seminal data of 300 males (mean age 34.6 ± 9.1 years) who spontaneously referred to our center of reproductive medicine. The evaluation of adherence to MD was performed with a validated 14-point Mediterranean Diet Adherence Screener (MEDAS) questionnaire. Our findings showed that sperm parameters such as sperm count, motility, viability and normal morphology are significantly and positively correlated with MEDAS, independently of BMI and age. In addition, the application of an ROC curve on MEDAS value vs. seminal alterations identified 6.25 as the score threshold value below which altered sperm parameters were more likely to occur [AUC = 0.096 (CI: 0.059-0.133; p < 0.00)]. Therefore, adhering to the MD with at least a MEDAS score of 6.26 increases the probability of normozoospermia. Moreover, subjects who had a MEDAS value lower than 6.25 had an Odds Ratio of 6.28 (CI = 3.967-9.945) for having at least one altered sperm parameter compared to those who were more adherent to the MD. In conclusion, our findings show that a higher adherence to the MD is associated with better semen parameters, in particular in relation to sperm count, sperm concentration, typical sperm morphology, and sperm progressive motility.

Kidney function impairment in men with primary infertility: A case-control analysis

BACKGROUND

Infertile men have a worse overall health status than their fertile counterparts.

OBJECTIVE

We aimed to (1) compare kidney function in men presenting for primary couple's infertility with that of fertile men and (2) assess kidney function impairment toward sperm quality in infertile men.

MATERIALS AND METHODS

In this case-control study, 387 consecutive white-European infertile men were matched by age with 134 same-ethnicity fertile men. Complete clinical and laboratory data were available for each patient. The Chronic Kidney Disease Epidemiology Collaboration function was used for estimated glomerular filtration rate calculation. Kidney functional impairment was defined as an estimated glomerular filtration rate <90 mL/min per 1.73 m2 , according to the Kidney Disease Improving Global Outcomes criteria. Multivariable logistic regression analysis was used to (1) assess the association between kidney function impairment and infertility status and (2) investigate the association between kidney function and semen analysis abnormalities in infertile men.

RESULTS

After matching, 34 (8.8%) infertile men depicted at least a mild unknown impairment of kidney function compared to only four (3%) fertile men, with four (3%) of the infertile presenting with an overt kidney function impairment (estimated glomerular filtration rate <60 mL/min per 1.73 m2 ). There were no differences in terms of age, body mass index and rate of comorbidities between the two groups (all p > 0.05). After adjusting for major confounders, infertility status was associated with a higher risk of reduced estimated glomerular filtration rate (odds ratio 3.20; 95% confidence interval 1.21-5.2; p = 0.002). Conversely, estimated glomerular filtration rate was not associated with sperm abnormalities in infertile men.

CONCLUSIONS

Mild kidney function impairment was found in 9% of asymptomatic and unaware men presenting for primary couple's infertility investigation. This novel finding corroborates growing data on a significant association of male infertility with a poorer overall male health status and the need for tailored preventive strategies.

Does Air Pollution Impact on Semen Parameters? Findings from a Real-Life, Cross-Sectional Study in Italian Infertile Men

PURPOSE

In industrialized countries, air pollutants levels have been monitored closely for environmental and research issues. Using Italian data, we aimed to investigate the association between air pollutants levels and semen parameters in a cohort of non-Finnish white-European men presenting for couple's infertility.

MATERIALS AND METHODS

Complete demographic and laboratory data from 1,152 infertile men consecutively assessed between January 2015 and January 2018 were analyzed. Semen analyses were based on the 2010 World Health Organization reference criteria. Health-significant comorbidities were scored with the Charlson Comorbidity Index (CCI). We analyzed the annual average level of the three main markers of air pollution (Pm10, Pm2.5, and NO₂) between 2014 and 2018. Descriptive statistics, linear and logistic regression analyses tested the association between air pollutants levels and semen parameters.

RESULTS

Of 1,152 men, 87 (7.55%) had normal sperm parameters at first semen analysis. Of 1,065 patients with abnormal semen analyses, 237 (22.25%), 324 (30.42%), and 287 (26.95%) patients presented 1, 2 or 3 abnormalities, respectively, and 217 (20.38%) were azoospermic. At linear regression analysis, Pm10, Pm2.5, and NO₂ were negatively associated with sperm morphology (Pm10: β=-0.5288 µg/m³, p=0.001; Pm2.5: β=-0.5240 µg/m³, p=0.019; NO₂: β=-0.4396 µg/m³, p<0.0001). Furthermore, the adjusted odds of normal sperm morphology <4% were 1.06 (95% confidence interval [CI], 1.03-1.09; p=0.007) for Pm10, 1.07 (95% CI, 1.03-1.11; p=0.007) for Pm 2.5, and 1.03 (95% CI, 1.02-1.05; p=0.001) for NO₂, respectively.

CONCLUSIONS

In a large homogenous cohort of infertile men, Pm10, Pm 2.5, and NO₂ levels were negatively associated with sperm morphology. Conversely, no clear association was observed with other macroscopic sperm parameters.

The Association between Monthly, Yearly, and Lifetime Cannabis Use, and Semen Parameters in Asian-American Men

PURPOSE

Medicinal and recreational cannabis use has grown exponentially, however, its effect on testicular function and spermatogenesis remains uncertain. The aim of this study was to evaluate the association between cannabis use and semen parameters in a cohort of Asian-American men with unknown fertility.

MATERIALS AND METHODS

Asian men were recruited to complete an online survey and submit a semen sample. Semen analysis, demographic data, lifestyle factors, and cannabis use habits were collected. Linear and logistic regression analyses were used to determine.

RESULTS

Among the 112 men included in this study, 51 used cannabis at least once in their lifetime, 30 men used cannabis at least once in the last 12 months, and 26 men used cannabis at least once in the last 30 days. Adjusted linear regression analyses identified an association between cannabis use in the previous 30 days and worse sperm morphology (β: -0.45, p=0.025) and sperm motility (β: -1.64, p=0.016). However, when stratifying by subfertile semen quality (i.e., WHO criteria), no association was identified between semen quality and cannabis use. Lower sperm morphology and motility are partially associated with recent cannabis use, while all other semen parameters are not.

CONCLUSIONS

We did not observe any consistent associations between cannabis use on any semen parameters in Asian-American men. Further studies within the field are needed to explore racial and ethnic differences in semen quality and lifestyle factors.

Testosterone deficiency and metabolic disturbances in men who fathered a child by use of donated spermatozoa

Dose–response association between level of impairment of semen quality and risk of morbidity or premature death has been reported. Therefore, it can be presumed that men utilizing donated spermatozoa, i.e. patients with non-obstructive azoospermia, are at highest risk for adverse health outcomes. To evaluate the risks of prescription of medications for common metabolic disturbances and testosterone replacement therapy (TRT) among men who father children with donated spermatozoa—who presumably do it due to severe impairment of fertility. We used Swedish nationwide register data on all fathers who had a live-born child between 2007 and 2014 in order to compare men who fathered children with donated spermatozoa to the ones who became fathers by using own gametes. Cox regression analysis was used in order to estimate the post-conception incidence of prescription of medicines for hypertension (HT), diabetes (type 1 and 2), dyslipidaemia (DLE) or TRT. Starting the follow up at time of conception, models were adjusted for age, educational level, and previous cancer treatment. In total 410,119 childbirths were included in the analysis. Among them, for 390 fathers donated spermatozoa were utilized. Fathers to children conceived with donated spermatozoa had higher risk for having TRT prescribed (HR: 18.14; 95%CI: 11.71–28.10; p ≪ 0.001). Same was true for DLE (HR: 2.08; 95%CI: 1.27–3.39; p = 0.003) but not diabetes. Fathers to children conceived by use of donated spermatozoa are at significantly increased risk for testosterone treatment and dyslipidaemia, necessitating stringent follow up and inclusion in prevention programs.

Effects of recreational cannabis on testicular function in primary infertile men

BACKGROUND

Male factor contributes to up to 50% of cases of couples experiencing infertility. Cannabis is one of the most commonly used recreational drugs and its effects on the reproductive system have been largely debated in the literature.

OBJECTIVES

The aim of this study is to evaluate the effect of recreational cannabis use on total T (tT) levels, gonadal status, and sperm parameters in a cohort of primary infertile non-Finnish, white-European men.

MATERIALS AND METHODS

Data of 2074 white-European men visited for primary couple's infertility were analyzed. Lifestyle factors and cannabis use were investigated in all participants. Semen analyses were based on the 2010 WHO reference criteria. Serum hormones were evaluated, and patients were subdivided based on their gonadal status. Health-significant comorbidities were scored with the Charlson Comorbidity Index (CCI). Descriptive statistics and linear regression analyses were used to test the association between cannabis use, sperm parameters, and hormonal levels. Logistic regression analyses tested potential predictors for abnormal sperm parameters and gonadal status.

RESULTS

Of 2074, 225 (10.9%) patients reported cannabis use in their lifetime. Total Testosterone levels were lower in cannabis users compared to non-users (p = 0.03). In a multivariable linear regression analysis, cannabis use was inversely associated with tT levels (ß = -0.372 ng/mL; p = 0.005) but not with FSH nor with LH levels. Conversely, at multivariable logistic regression model cannabis use was not associated with the type of hypogonadism. At multivariable linear regression analysis, cannabis use was inversely associated with sperm morphology (p = 0.007), while not with both sperm concentration and sperm motility. Similarly, at adjusted logistic regression analysis cannabis use resulted associated with teratozoospermia (p = 0.039), but not with oligo-, astheno- and azoospermia.

CONCLUSIONS

Infertile men using cannabis are at higher risk of having lower testosterone levels and altered sperm morphology as compared with non-users. This article is protected by copyright. All rights reserved.

Triglycerides/Glucose Index is Associated with Sperm Parameters and Sperm DNA Fragmentation in Primary Infertile Men: A Cross-Sectional Study

Study question: we aimed to investigate the relationship between the tyg index and both semen and hormonal characteristics in a cohort of primary infertile men. Summary answer: almost one in two primary infertile men presented with a triglycerides/glucose index (tyg) suggestive of insulin resistance (ir). overall, patients with tyg suggestive of ir showed worse clinical, hormonal, and semen parameters. What is already known: male factor infertility (MFI) is often associated with metabolic disorders such as diabetes mellitus and metabolic syndrome, where insulin resistance (IR) plays a relevant pathological role. Recently, TyG has been suggested as a user-friendly IR marker. Study Design: serum hormones and the sperm DNA fragmentation index (SDF) were measured in every patient. The semen analysis was based on 2010 WHO reference criteria. Glucose and insulin levels were measured for every man after a 12-h overnight fast, and the homeostatic model assessment index (HOMA-IR) was then calculated and categorized using a 2.6 threshold. Similarly, fasting glucose and triglycerides levels were measured and the TyG index was calculated and categorized using an 8.1 threshold. Descriptive statistics and logistic regression models tested the association between the TyG and semen and hormonal characteristics. Participants: complete demographic, clinical, and laboratory data from 726 consecutive white European primary infertile men were considered for this analysis. Main results and the role of chance: the median (IQR) age was 39 (35–43) years. A TyG and HOMA suggestive for IR was found in 339 (46.6%) and 154 (21.2%) men, respectively. During the Spearman’s test, the TyG index was highly correlated with HOMA-IR (rho = 0.46, p < 0.001). Compared to men with a normal TyG, men with TyG > 8.1 were older, had greater BMI and CCI scores, and lower total testosterone and sperm concentration, but higher DFI, and presented a greater proportion of NOA (all p < 0.01). The multivariable logistic regression analysis showed that men with TyG > 8.1 were at higher risk of SDF > 30 (OR 1.92 (CI: 1.2–2.9)) and NOA (OR 1.78 (CI: 1.1–2.8)). Wider implications of the findings: the Tyng index may act as a reliable marker of IR in the clinical work-up of primary infertile men in real-life settings.

Aging, inflammation and DNA damage in the somatic testicular niche with idiopathic germ cell aplasia

Molecular mechanisms associated with human germ cell aplasia in infertile men remain undefined. Here we perform single-cell transcriptome profiling to highlight differentially expressed genes and pathways in each somatic cell type in testes of men with idiopathic germ cell aplasia. We identify immaturity of Leydig cells, chronic tissue inflammation, fibrosis, and senescence phenotype of the somatic cells, as well markers of chronic inflammation in the blood. We find that deregulated expression of parentally imprinted genes in myoid and immature Leydig cells, with relevant changes in the ratio of Lamin A/C transcripts and an active DNA damage response in Leydig and peritubular myoid cells are also indicative of senescence of the testicular niche. This study offers molecular insights into the pathogenesis of idiopathic germ cell aplasia.

Molecular mechanisms associated with human germ cell aplasia in infertile men remain undefined. Here the authors perform single-cell transcriptome profiling to highlight differentially expressed genes and pathways in each somatic cell type in testes of men with idiopathic germ cell aplasia.

Association between obesity-associated markers and semen quality parameters and serum reproductive hormones in Chinese infertile men

BACKGROUND

The current evidence on the association between obesity-associated markers and semen quality, serum reproductive hormones and lipids remains inconsistent. In this study, we tested the hypothesis that, in infertile Chinese men, body mass index (BMI) negatively correlates with sperm concentration, serum total testosterone (TT), and high-density lipoprotein cholesterol (HDL-C). The relationship between other obesity-associated markers and semen quality parameters, serum reproductive hormones, lipids and leptin were also investigated.

METHODS

181 Chinese infertile men were recruited from September 2018 to September 2019. Their obesity-associated markers, semen parameters, and serum reproductive hormones, lipids and leptin were detected. Statistical analysis was performed to assess the relationship between obesity-associated markers and semen quality, serum reproductive hormones, lipids and leptin.

RESULT(S)

Statistically negative correlation was found between other obesity-associated markers (e.g. waist-to-hip ratio and waist-to-height ratio) and semen parameters (e.g. sperm concentration, ratio of progressive motility and ratio of non-progressive motility), while no significant correlation was found between BMI and semen quality, serum reproductive hormones, lipids and leptin. Ratio of morphologically normal sperm was negatively correlated with serum lipids including total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), leptin and seminal superoxide dismutase. Ratio of progressive sperm, sperm concentration and ratio of morphologically normal sperm exhibited significantly lower values in overweight group than normal group. Estradiol (E2) and E2/TT were significantly higher in obese group than normal group, while TT level was significantly lower in obese group than normal group. Univariate and multivariate analysis indicated that TC was significantly associated with BMI. Serum leptin concentration was positively correlated with seminal leptin concentration in overweight and obese groups.

CONCLUSION(S)

No significant correlation was found between BMI and sperm concentration, serum TT and HDL-C, while other obesity-associated markers were found to negatively correlate with sperm concentration, ratio of progressive motility and ratio of non-progressive motility. Statistically significant correlations between serum reproductive hormones, lipids and leptin also existed in Chinese infertile men.