Self-rated health and semen quality among 3,457 young Danish men

Self-Rated Health and Semen Quality in Men Undergoing Assisted Reproductive Technology

Importance

Numerous studies have documented the association of self-rated health (SRH) with chronic diseases. However, few studies have investigated its association with semen quality.

Objective

To examine the association of SRH with semen quality among men undergoing assisted reproductive technology (ART) in China.

Design, Setting, and Participants

This cross-sectional study recruited male partners in couples undergoing ART treatment at the Center for Reproductive Medicine, Tongji Hospital, Wuhan, China. A total of 1262 men underwent 2 semen examinations and completed a questionnaire on SRH between December 2018 and January 2020. Data analysis was performed from November 20, 2022, to March 24, 2023.

Exposure

SRH, including overall physical and mental health, as well as reproductive-related physical and mental health specifically, were reported at baseline recruitment.

Main Outcomes and Measures

Sperm concentration, sperm progressive motility, sperm motility, and sperm count as semen quality parameters.

Results

The study included 1262 men with a mean (SD) age of 32.79 (5.25) years and body mass index of 24.37 (3.68). Men with poorer SRH had lower semen quality (eg, sperm concentration among poor vs very good overall physical health: percentage variation, -14.67%; 95% CI, -23.62% to -4.66%). Among 4 components of SRH, a greater reduction in semen quality was estimated for reproductive-related SRH compared with overall SRH, whereas the greatest reduction was observed for reproductive-related physical SRH. In comparison with men with very good reproductive-related physical SRH, men with poor reproductive-related physical SRH had differences of -24.78% (95% CI, -32.71% to -15.93%) and -25.61% (95% CI, -33.95% to -16.22%) in sperm count and concentration, respectively, and regression coefficients of -9.38 (95% CI, -12.01 to -6.76) and -9.24 (95% CI, -11.82 to -6.66) for sperm motility and sperm progressive motility, respectively.

Conclusions and Relevance

In this cross-sectional study of Chinese men, poorer SRH was associated with lower semen quality, and reproductive-related physical SRH was the most pronounced indicator. Our findings suggest that SRH, especially reproductive-related physical SRH, was a good indicator of semen quality, which should inform public and clinical regulatory decisions.

A history of cryptorchidism is associated with impaired testicular function in early adulthood: a cross-sectional study of 6376 men from the general population

STUDY QUESTION

Is there a difference in testicular function in early adulthood between men born with cryptorchidism and men born with normally descended testes?

SUMMARY ANSWER

In men from the general population, a history of cryptorchidism was associated with lower total testis volume and impaired semen quality as well as altered serum levels of reproductive hormones.

WHAT IS KNOWN ALREADY

The association between cryptorchidism and testicular function is well documented in studies based on sub-fertile or infertile men recruited from a clinical setting. However, the association has not previously been investigated in men from the general population, who were unselected regarding fertility status.

STUDY DESIGN, SIZE, DURATION

This is a cross-sectional population-based study of 6376 young Danish men examined from 1996 to 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study is based on young men from the greater Copenhagen area, Denmark (median age of 19 years) who were unselected regarding fertility status and semen quality. The young men delivered a semen sample, had a blood sample drawn and underwent a physical examination including assessment of testis volume. Participants completed a questionnaire regarding cryptorchidism at birth, current lifestyle and their mother’s pregnancy, after consulting their mother. The differences in markers of testicular function, including testis volume, semen parameters and reproductive hormones between men with and without a history of cryptorchidism were investigated with multiple linear regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

The participation rate was 24% for the entire study period. Overall, a history of cryptorchidism was associated with reduced testicular function. In the adjusted models, a history of cryptorchidism was associated with a 3.5 ml lower total testis volume, determined by orchidometer (P < 0.001), 28% lower sperm concentration (95% CI: −37 to −20) and 26% lower inhibin B/FSH ratio (95% CI: −50 to −22) compared to men without a history of cryptorchidism, suggesting a reduced spermatogenetic capacity. Men with a history of cryptorchidism also had a slightly reduced Leydig cell function expressed as a 6% lower testosterone/LH ratio (95% CI: −12 to −0.7). The significant effect sizes and different markers of testicular function pointing in the same direction across the different models based on a large sample size support that the results are not chance findings.

LIMITATIONS, REASONS FOR CAUTION

Information on cryptorchidism at birth and treatment modus was obtained by retrospective self-report, and each participant only delivered one semen sample.

WIDER IMPLICATIONS OF THE FINDINGS

The results suggest that men with a history of cryptorchidism could be at increased risk of experiencing fertility problems. However, among these men there is a wide variation in semen quality and further research is needed in order to identify the subgroup of boys born with cryptorchidism who are at the greatest risk of impaired semen quality when reaching adulthood.

STUDY FUNDING/COMPETING INTEREST(S)

The study received financial support from the Research fund of Rigshospitalet, Copenhagen University Hospital; the European Union (Contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603. FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers Foundation; and Svend Andersens Foundation. None of the founders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions. The authors have nothing to declare.

TRIAL REGISTRATION NUMBER

N/A.

Anogenital distance is associated with semen quality but not reproductive hormones in 1106 young men from the general population

STUDY QUESTION

Is anogenital distance (AGD) associated with semen quality and reproductive hormones in men from the general population?

SUMMARY ANSWER

Short AGD measured from the anus to the base of scrotum (AGDAS) was associated with reduced sperm counts and morphology but not with sperm motility or reproductive hormones.

WHAT IS KNOWN ALREADY

AGD is longer in males than in females. In rodents, AGD is a well-established and sensitive marker of disruption during the masculinization programming window in utero and it has been suggested to be so in humans as well. Therefore, the average AGD would be expected to be shorter in men with poor semen quality, which some studies have confirmed while others have not.

STUDY DESIGN, SIZE, DURATION

This cross-sectional population-based study was of 1106 men included between 2012 and 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Men from the general Danish population (median age 19 years), unselected with regard to fertility status and semen quality, delivered a semen sample, had a blood sample drawn, which was analyzed for concentrations of reproductive hormones, and answered a comprehensive questionnaire. They also had a physical examination performed including determination of AGD measured as the distance between anus and scrotum (AGDAS) and penis (AGDAP). Odds ratios (OR) and 95% CI were estimated for a man having abnormal semen parameters according to the World Health Organization's reference values or a low/high concentration of reproductive hormones (defined as the lowest or highest 10%) depending on AGD. AGD was categorized in four strata: ≤10th percentile, 10th-30th percentile, 30th-50th percentile and >50th percentile.

MAIN RESULTS AND THE ROLE OF CHANCE

Men with the 10% shortest AGDAS had a more than doubled risk (OR: 2.19, 95% CI: 1.40-3.42) of being in the subfertile range for either sperm concentration (<15 million/mL) or sperm morphology (<4%) compared to men with AGDAS above the median (reference). Men in the 10th-30th percentile also had an increased OR of 1.48 (95% CI: 1.06-2.08) but not men in the 30th-50th percentile (OR: 1.14, 95% CI: 0.81-1.62). AGDAP was only weakly related to semen quality. AGD was not associated with testicular volume or any of the reproductive hormones.

LIMITATIONS, REASONS FOR CAUTION

Limitations include the potential non-differential misclassification of reproductive outcomes based on a single semen and blood sample and some between-examiner differences in AGD measurements which introduces noise and may result in an underestimation of observed associations.

WIDER IMPLICATIONS OF THE FINDINGS

Our study of men from the general population confirmed associations between AGD and semen quality, supporting the hypothesis that AGD in humans could be a marker of fetal testicular development. This suggests that the low semen quality in Danish men may partly be explained by prenatal factors.

STUDY FUNDING/COMPETING INTEREST(S)

The study has received financial support from the ReproUnion (L.P.); the Research fund of Rigshospitalet, Copenhagen University Hospital (N.J.); Grants R01ES016863-04 and R01ES016863-02S4; National Institute of Environmental Health Sciences (NIEHS) and National Institute of Environmental Health Sciences grant (P30ES023515) (S.S.); the European Union (Contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603, FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers foundation; and Svend Andersens Foundation. None of the funders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions. The authors have nothing to declare.

TRIAL REGISTRATION NUMBER

N/A.

Semen Quality as a Predictor of Subsequent Morbidity: A Danish Cohort Study of 4,712 Men With Long-Term Follow-up

Semen quality has been suggested to be a biological marker of long-term morbidity and mortality; however, few studies have been conducted on this subject. We identified 5,370 men seen for infertility at Frederiksberg Hospital, Denmark, during 1977-2010, and 4,712 of these men were followed in the Danish National Patient Registry until first hospitalization, death, or the end of the study. We classified patients according to hospitalizations and the presence of cardiovascular disease, diabetes, testicular cancer, or prostate cancer. We found a clear association between sperm concentration below 15 million/mL and all-cause hospitalizations (hazard ratio = 1.5, 95% confidence interval: 1.4, 1.6) and cardiovascular disease (hazard ratio = 1.4, 95% confidence interval: 1.2, 1.6), compared with men with a concentration above 40 million/mL. The probabilities for hospitalizations were also higher with a low total sperm count and low motility. Men with a sperm concentration of 195-200 million/mL were, on average, hospitalized for the first time 7 years later than were men with a sperm concentration of 0-5 million/mL. Semen quality was associated with long-term morbidity, and a significantly higher risk of hospitalization was found, in particular for cardiovascular diseases and diabetes mellitus. Our study supports the suggestion that semen quality is a strong biomarker of general health.

In utero exposure to di-(2-ethylhexyl) phthalate induces testicular effects in neonatal rats that are antagonized by genistein cotreatment

Fetal exposure to endocrine disruptors (EDs) is believed to predispose males to reproductive abnormalities. Although males are exposed to combinations of chemicals, few studies have evaluated the effects of ED mixtures at environmentally relevant doses. Our previous work showed that fetal exposure to a mixture of the phytoestrogen genistein (GEN) and the plasticizer di-(2-ethylhexyl) phthalate (DEHP) induced unique alterations in adult testis. In this follow-up study, we examined Postnatal Day 3 (PND3) and PND6 male offspring exposed from Gestational Day 14 to parturition to corn oil, 10mg/kg GEN, DEHP, or their combination, to gain insight into the early molecular events driving long-term alterations. DEHP stimulated the mRNA and protein expression of the steroidogenic enzyme HSD3B, uniquely at PND3. DEHP also increased the mRNA expression of Nestin, a Leydig progenitor/Sertoli cell marker, and markers of Sertoli cell (Wt1), gonocyte (Plzf, Foxo1), and proliferation (Pcna) at PND3, while these genes were unchanged by the mixture. Redox (Nqo1, Sod2, Sod3, Trx, Gst, Cat) and xenobiotic transporter (Abcb1b, Abcg2) gene expression was also increased by DEHP at PND3, while attenuated when combined with GEN, suggesting the involvement of cellular stress in short-term DEHP effects and a protective effect of GEN. The direct effects of GEN and mono-(2-ethylhexyl) phthalate, the principal bioactive metabolite of DEHP, on testis were investigated in PND3 organ cultures, showing a stimulatory effect of 10 μM mono-(2-ethylhexyl) phthalate on basal testosterone production that was normalized by GEN. These effects contrasted with previous reports of androgen suppression and decreased gene expression in perinatal rat testis by high DEHP doses, implying that neonatal effects are not predictive of adult effects. We propose that GEN, through an antioxidant action, normalizes reactive oxygen species-induced neonatal effects of DEHP. The notion that these EDs do not follow classical dose-response effects and involve different mechanisms of toxicity from perinatal ages to adulthood highlights the importance of assessing impacts across a range of doses and ages.

Invited commentary: sleep disturbances--another threat to male fecundity?

In a cross-sectional study among 953 young Danish men (2008-2011), Jensen et al. reported that sleep disturbances showed inverse U-shaped associations with semen parameters and testis size (Am J Epidemiol. 2013;177(10):1027-1037). Sleep disturbances were associated with several factors likely to affect semen parameters (such as history of sexually transmitted infections) that cannot all be efficiently controlled for, leaving room for residual confounding. Future studies could adopt a longitudinal design and rely on objective personal measures of sleep quality and duration using accelerometers. Intervention studies would also be helpful to identify whether sleep disturbances (or improvement of sleep quality) can lead to short-term variations in semen parameters. This study adds another suspect to the list of factors possibly influencing male fecundity potential, which also includes overweight, exposure to tobacco smoke (in adulthood and in utero), exposure to specific persistent (lead, organic pollutants) and nonpersistent (some phthalates, bisphenol A) environmental pollutants, and exposure to atmospheric pollutants. Even if each of these factors has a weak impact at the individual level, the large number of factors and the relatively high prevalence of exposure in the general population make it likely that at the population level, lifestyle and environmental factors put a high burden on male fecundity potential.

Endocrine-disrupting chemicals: associated disorders and mechanisms of action

The incidence and/or prevalence of health problems associated with endocrine-disruption have increased. Many chemicals have endocrine-disrupting properties, including bisphenol A, some organochlorines, polybrominated flame retardants, perfluorinated substances, alkylphenols, phthalates, pesticides, polycyclic aromatic hydrocarbons, alkylphenols, solvents, and some household products including some cleaning products, air fresheners, hair dyes, cosmetics, and sunscreens. Even some metals were shown to have endocrine-disrupting properties. Many observations suggesting that endocrine disruptors do contribute to cancer, diabetes, obesity, the metabolic syndrome, and infertility are listed in this paper. An overview is presented of mechanisms contributing to endocrine disruption. Endocrine disruptors can act through classical nuclear receptors, but also through estrogen-related receptors, membrane-bound estrogen-receptors, and interaction with targets in the cytosol resulting in activation of the Src/Ras/Erk pathway or modulation of nitric oxide. In addition, changes in metabolism of endogenous hormones, cross-talk between genomic and nongenomic pathways, cross talk with estrogen receptors after binding on other receptors, interference with feedback regulation and neuroendocrine cells, changes in DNA methylation or histone modifications, and genomic instability by interference with the spindle figure can play a role. Also it was found that effects of receptor activation can differ in function of the ligand.

Long-term testicular position and growth of acquired undescended testis after prepubertal orchidopexy

PURPOSE

The aim of the study was to determine long-term testicular position and growth of acquired undescended testis (UDT) after prepubertal orchidopexy.

METHODS

Patients who had undergone prepubertal orchidopexy for acquired UDT at our hospital between 1986 and 1999 were recruited to assess long-term testicular position and volume. Testis position was assessed by physical examination. Testis volume was measured with Prader orchidometry and ultrasound and was compared with normative values reported in the literature.

RESULTS

A total of 105 patients (aged 14.0-31.6 years) were included with 137 acquired UDT (32 bilateral, 33 left sided, and 40 right sided). All but 1 of the orchidopexied testes (99.3%) were in low scrotal position. The mean volume of the orchidopexied testes in unilateral UDT (n = 73, 10.57 ± 3.74 mL) differed significantly from the size of the testes at the contralateral side (14.11 ± 4.23 mL) (P = .000). The operated testes (10.28 ± 3.45 mL) were smaller than the mean adult testis volume reported in the literature (13.4-13.6 mL; cutoff, 13.2 mL).

CONCLUSION

Testis position after prepubertal orchidopexy for acquired UDT was nearly always low scrotal. The volume of the orchidopexied testes was smaller than both the volume of the contralateral testes and the normative values reported in the literature.

Human semen quality in the new millennium: a prospective cross-sectional population-based study of 4867 men

OBJECTIVES

Considerable interest and controversy over a possible decline in semen quality during the 20th century raised concern that semen quality could have reached a critically low level where it might affect human reproduction. The authors therefore initiated a study to assess reproductive health in men from the general population and to monitor changes in semen quality over time.

DESIGN

Cross-sectional study of men from the general Danish population. Inclusion criteria were place of residence in the Copenhagen area, and both the man and his mother being born and raised in Denmark. Men with severe or chronic diseases were not included.

SETTING

Danish one-centre study.

PARTICIPANTS

4867 men, median age 19 years, included from 1996 to 2010.

OUTCOME MEASURES

Semen volume, sperm concentration, total sperm count, sperm motility and sperm morphology.

RESULTS

Only 23% of participants had optimal sperm concentration and sperm morphology. Comparing with historic data of men attending a Copenhagen infertility clinic in the 1940s and men who recently became fathers, these two groups had significantly better semen quality than our study group from the general population. Over the 15 years, median sperm concentration increased from 43 to 48 million/ml (p=0.02) and total sperm count from 132 to 151 million (p=0.001). The median percentage of motile spermatozoa and abnormal spermatozoa were 68% and 93%, and did not change during the study period.

CONCLUSIONS

This large prospective study of semen quality among young men of the general population showed an increasing trend in sperm concentration and total sperm count. However, only one in four men had optimal semen quality. In addition, one in four will most likely face a prolonged waiting time to pregnancy if they in the future want to father a child and another 15% are at risk of the need of fertility treatment. Thus, reduced semen quality seems so frequent that it may impair the fertility rates and further increase the demand for assisted reproduction.

Has fertility declined in recent decades?

OBJECTIVE

Increasing use of infertility treatment and a decline in demographic fertility in some countries have raised concern whether human fecundity is declining or has declined over time. A dramatic decline in semen quality over the past half-century has been proposed and widely discussed, but none of the existing studies provide data good enough for coming to any firm conclusion.

RESULTS

Results from 19 articles published during the last 5 years on semen quality and fecundity, covering data from the Nordic countries since the year 2000, do not indicate an ongoing decline in fertility.

CONCLUSION

We will probably never know, whether semen quality and fecundity has declined over time, but we may be able to monitor biological fecundity and semen quality over time from now on. There are both research initiatives and interest from official channels that could provide more funding for infertility research.

Is self-rated health associated with blood immune markers in healthy individuals?

BACKGROUND

Although self-rated health (SRH) has been established as a robust predictor of morbidity and mortality, the immunological mechanisms underpinning this relationship are poorly understood.

PURPOSE

This study examined the association of SRH with humoral and cellular immune markers in healthy individuals who reported no physical illnesses.

METHOD

A total of 116 healthy Japanese white-collar employees (79 women and 37 men) at a pharmaceutical company, aged 23-62 (mean 32) years, underwent a blood draw for the measurement of circulating immune (T, B, and natural killer) cells, inflammatory cytokines (interleukin-6 and tumor necrosis factor-alpha), and plasma immunoglobulin G (IgG) and completed a health survey including SRH. The question regarding SRH ranged from "very good" (coded 1) to "very poor" (coded 5). Hierarchical multiple regression analysis was carried out to calculate the relationship between SRH and immune markers.

RESULTS

In this sample, poor SRH was positively correlated with B (CD19(+)) cell numbers (beta = 0.260, p < 0.05) and IgG levels (beta = 0.335, p < 0.01) even after adjusting for depressive symptoms, age, education, marital status, smoking, alcohol consumption, physical activity, body mass index, sex, and sex x SRH interaction. The interaction between SRH and sex on the immune markers was not significant.

CONCLUSION

Although the connection between SRH and immune markers was not strong in this context, the results suggest that poor SRH may be associated with reduced humoral immune system capacity to respond to new/latent challenges. The results provide some support for the immunological basis of SRH in healthier individuals.

Increased sperm count may account for high population frequency of factor V Leiden

BACKGROUND

Factor V Leiden (FVL) increases the risk of venous thrombosis and pregnancy loss in carriers. Nevertheless, this relatively old mutation is prevalent in Caucasion populations, which could be explained by positive selection pressure. Men with FVL have previously been found to have higher fecundity (the time between marriage and first pregnancy). Whether this is caused by increased sperm counts in men with FVL is unknown.

OBJECTIVES

To assess whether men with factor V Leiden have increased sperm counts.

PATIENTS/METHODS

We performed a prospective cohort study among 1139 consecutively included male partners of subfertile couples presenting at our university hospital for fertility workup between January 2000 and July 2007. All potential candidates who gave informed consent were included, irrespective of their fertility workup. In this retrospective analysis, we excluded participants with known causes of spermatogenic function or azoospermia. Subsequently, we genotyped all participants and compared sperm counts between FVL carriers and non-carriers.

RESULTS

We identified 37 FVL carriers and 921 non-carriers. FVL carriers had higher total sperm counts and total motile sperm counts than non-carriers: 236 x 10(6) (95% CI 158-292 x 10(6)) vs. 163 x 10(6) (95% CI 147-178 x 10(6)) and 81 x 10(6) (95% CI 54-105 x 10(6)) vs. 52 x 10(6) (95% CI 48-57 x 10(6)), respectively.

CONCLUSIONS

To our knowledge, this is the first study that indicates that an increased incidence of a genotype may be controlled by increased sperm counts. However, the finding that men with FVL had higher total (motile) sperm counts was not statistically significant and needs confirmation in other studies.