Factors associated with male infertility: a case-control study of 218 infertile and 240 fertile men

GRPR down-regulation inhibits spermatogenesis through Ca2+ mediated by PLCβ/IP3R signaling pathway in long-term formaldehyde-exposed rats

Formaldehyde (FA), which is known as an air pollutant, has been proven to induce male infertility. However, the underlying mechanism of FA-induced male infertility remains elusive. In this study, 24 male SD rats were exposed to different levels of FA (0, 0.5, 2.46, and 5 mg/m3) for eight consecutive weeks. Through HE staining and sperm smear, we observed that FA exposure resulted in spermatogenic injury and the sperm quality decreased in rats. The qRT-PCR and Western blot analysis further revealed that GRPR was down-regulated in testicular tissues of FA-exposed rats as well as primary spermatogenic cells. Meanwhile, ZDOCK uncovered an interaction between GRPR and PLCβ. In addition, the CCK8, Fluo 3-AM and Flow cytometry results showed that FA exposure suppressed the expression of GRPR, PLCβ and IP3R, consequently reducing the Ca2+ concentration in spermatogenic cells, inducing apoptosis and inhibiting proliferation of spermatogenic cells. Moreover, rescue experiments confirmed that promoting GRPR could improve intracellular Ca2+ concentration by upregulating PLCβ and IP3R, partially reducing the apoptosis and promoting the proliferation of FA-treated spermatogenic cells. These findings revealed that GRPR participates in spermatogenesis through Ca2+ mediated by the PLCβ/IP3R signaling pathway in FA-exposed rats.

Environmental and occupational factors and higher risk of couple infertility: a systematic review study

Background

Infertility is a global health problem that represents an increasing trend due to new lifestyles following technological advances since individuals are facing more risk factors than before. The present systematic review study aimed to investigate the impact of environmental and occupational factors on reproductive parameters and increased risk of couple infertility.

Main body

Scopus, PubMed, SID, and Web of Science databases were searched for the available observational (i.e., cohort, case-control, and cross-sectional) systematic review, meta-analysis, and clinical trial studies between 2007 and 2019. To this end, keywords such as ‘Environmental exposure’, ‘Occupational exposure’, ‘Environmental pollutants’, ‘Environmental pollution’, ‘Couple infertility’, ‘Sterility’, and ‘Sub-fertility’ were used. The retrieved investigations examined the impact of environmental and occupational risk factors on reproductive indices and increased infertility risk. Totally, 66 out of 9519 papers were evaluated after considering the inclusion and exclusion criteria. The reported risk factors in the reviewed studies were heavy metals, cigarette smoking, and exposure to chemicals through consumer goods, urban life, and proximity to main roads. In addition, occupational factors included heavy physical activity, prolonged sitting, exposure to a hot environment, contact with formaldehyde, pesticides, insecticides, mechanical vibration, and contact with ionizing radiation, all of which affected the reproductive parameters. However, some researchers found no significant associations in this regard.

Short conclusion

In general, individuals with known impairments in reproductive parameters were more exposed to risk factors. Nonetheless, more studies are needed to determine the risk of infertility in the population.

Effect of Rourea coccinea on ethanol-induced male infertility in Wistar albino rats

Ethanol consumption is a risk factor of male infertility. The use of medicinal plants offers an alternative for the treatment of male infertility in developing countries. This study aimed to evaluate the Rourea coccinea effect on ethanol-induced male infertility in Wistar rats. Twenty-five (25) male Wistar rats were randomised into five groups of five rats and treated by oesophageal gavage over a 28-day period. Group 1 (negative control) received distilled water; Group 2 (positive control) received 30% ethanol at 7 mg/kg body weight; Group 3 (reference control) received 30% ethanol co-treated with the reference drug, clomiphene citrate; Groups 4 and 5 (test groups) received 30% ethanol co-treated with Rourea coccinea hydro-ethanolic extract at 200 and 400 mg/kg respectively. Testosterone hormone, sperm parameters and testicular histopathology were evaluated. Ethanol treatment induced a significant reduction (p < .05) in sperm count, motility, viability and a significant increase in sperm abnormalities because of the significant decrease (p < .05) in testosterone levels. These data correlate with the alterations observed in the seminiferous tubule on histopathological examination of the testes. However, co-treatment of ethanol with Rourea coccinea extract or the reference drug restored the ethanol-induced toxic effects on the reproductive organs, sperm profile and testosterone level.

The effect of hydroethanolic extract of Matricaria chamomilla on the reproductive system of male rats exposed to formaldehyde

Formaldehyde is a common agent in our surrounding environment and can adversely affect the male reproductive system. In this study, the effectiveness of Matricaria chamomilla (MC) extract as an antioxidant was investigated in rats treated with formaldehyde. Thirty-two male Wistar rats were randomly divided into six groups: F (10 mg/kg formaldehyde), M200 (200 mg/kg MC extract), M500 (500 mg/kg MC extract), FM200 (10 mg/kg formaldehyde and 200 mg/kg MC extract), FM500 (10 mg/kg formaldehyde and 500 mg/kg MC extract) and control group (0.9% normal saline). Formaldehyde and MC extract were administered daily for 30 consecutive days via intraperitoneal injection. Hormonal status, sperm parameters, testis tissue histology, germinal cells apoptosis and stereological analyses of testis tissue were investigated. Testosterone and LH levels were significantly increased in FM200, FM500, F200 and F500 groups compared to F group (p ≤ 0.05). Sperm count, motility and viability were significantly enhanced in FM200, FM500, F200 and F500 groups compared to F group (p ≤ 0.05). A decrease in the number of apoptotic germ cells in FM200, FM500, M200 and M500 groups (p ≤ 0.05) was evident. In particular, the MC extract in dose 500 mg/kg is seen to reduce the adverse effects of formaldehyde on the reproductive system of male rats.

High regenerative capacity of the liver and irreversible injury of male reproductive system in carbon tetrachloride-induced liver fibrosis rat model

BACKGROUND

Liver fibrosis (LF) is a chronic disease, associated with many collateral diseases including reproductive dysfunction. Although the normal liver has a large regenerative capacity the complications of LF could be severe and irreversible. Hormone and sex-related issues of LF development and interactions with male reproductive have not been finally studied. The aim was to study the reproductive function of male rats in experimental CCl4-induced liver fibrosis rat model, and the capability for restoration of both the liver and male reproduction system.

MATERIALS

Studies were conducted on 20 3-month old Wistar male rats. The experimental animals were injected with freshly prepared 50% olive oil solution of carbohydrate tetrachloride (CCl4). On the 8th week after injection we noted the manifestations of liver fibrosis. The rats were left to self-healing of the liver for 8 weeks. All male rats underwent ultrasound and biopsy of the liver and testes on the 8th and 16th weeks. The male rats were mated with healthy females before CCl4 injection, after modeling LF on the 8th week, and after self-healing of the liver. Pregnancy was monitored on ultrasound.

RESULTS

On the 8th week of experiment we observed ultrasound manifestation of advanced liver fibrosis, including hepatosplenomegaly, portal hypertension. Ultrasound exam of the rat testes showed testicular degeneration, hydrocele, fibrosis, scarring, petrifications, size reduction, and restriction of testicular descent; testes size decreased from 1.24 ± 0.62 ml to 0.61 ± 0.13, p < 0.01. Liver histology showed granular dystrophy of hepatocytes, necrotic areas, lipid inclusions in parenchyma. Rats with liver fibrosis demonstrated severe injury of the reproductive system and altering of fertility: the offspring of male rats with advanced LF was 4.71 ± 0.53 born alive vs 9.55 ± 0.47 born from mating with healthy males, p < 0.001. Eight weeks after last CCl4 injection, we revealed signs of liver regeneration, significant recovery of its structure. The ALT and AST levels significantly decreased and reached background measurements. As a result of the second interbreeding after liver self-healing no significant difference was found vs previous mating.

CONCLUSION

Carbohydrate tetrachloride induces injury of liver parenchyma evoking fast and severe liver fibrosis, and is associated with irreversible structural and functional changes in testes, reducing fertility, decreasing potential pregnancy rate, and affecting its development. Liver showed high potential to regenerate, however the self-restoring after liver fibrosis was not accompanied with recovery of the reproductive system.

Testicular and epididymal toxicity induced by benzo(a)pyrene, alcohol, and their combination in Wistar rats

Alcoholism and cigarette smoking are pervasive problems that have been implicated in human health. In this study, independent and combinative toxicities of alcohol and benzo(a)pyrene (BaP) were tested for reproductive toxicity in rats. Male Wistar rats were exposed to BaP (100 μg per kg body weight) on alternative days and alcohol (2 g per kg body weight per day) daily, either individually or in combination for 60 days. Exposure to BaP or alcohol significantly decreased the fertility index and reduced the number of implantations associated with elevated pre- and post-implantation losses. The relative weights of testes, epididymis, seminal vesicles, and prostate gland were significantly decreased in BaP or alcohol administered rats. Exposure to BaP or alcohol significantly decreased daily sperm production, sperm density, percentages of motile, viable, HOS-tail swelled sperm, testicular 3β- and 17β-hydroxysteroid dehydrogenase activity levels, mRNA levels of steroidogenic acute regulatory protein, and serum testosterone levels. Further, in silico studies revealed the binding of BaP at the hydrophobic tunnel of StAR protein. Additional studies disclosed stable interactions of BaP with the amide group of ASN150 and the hydroxyl group of THR263 by forming three hydrogen bonds. Our results also showed that treatment of rats with BaP or alcohol caused a marked increase in levels of superoxide anions, hydrogen peroxide, and lipid peroxidation in testis and epididymis. Conversely, glutathione levels and activity levels of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase in testis as well as epididymis decreased significantly in the experimental rats. Under the same conditions, increased fragmented DNA levels were observed in sperm. The results of the present study indicate that exposure to BaP or alcohol adversely affected the male reproductive functions, which may be, at least in part, due to androgen deficiency and/or oxidative stress-related mechanisms. Consistently, the present results also showed higher reproductive toxicity upon exposure to combinations of BaP and alcohol than upon their individual treatments. Therefore, this combination was classified as additive and synergistic responses of BaP and alcohol.

Acquired Cystic Fibrosis Transmembrane Conductance Regulator Dysfunction in Chronic Bronchitis and Other Diseases of Mucus Clearance

Chronic obstructive pulmonary disease (COPD) is a major public health problem. No therapies alter the natural history of the disease. Chronic bronchitis is perhaps the most clinically troublesome phenotype. Emerging data strongly suggest that cigarette smoke and its components can lead to acquired cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. Findings in vitro, in animal models, and in smokers with and without COPD also show acquired CFTR dysfunction, which is associated with chronic bronchitis. This abnormality is also present in extrapulmonary organs, suggesting that CFTR dysfunction may contribute to smoking-related systemic diseases.

Smoking and Male Infertility: An Evidence-Based Review

Many studies have reported that the contents of cigarette smoke negatively affect sperm parameters, seminal plasma, and various other fertility factors. Nevertheless, the actual effect of smoking on male fertility is not clear. The effect of smoking on semen parameters is based on the well-established biological finding that smoking increases the presence of reactive oxygen species, thereby resulting in oxidative stress (OS). OS has devastating effects on sperm parameters, such as viability and morphology, and impairs sperm function, hence reducing male fertility. However, not all studies have come to the same conclusions. This review sheds light upon the arguable association between smoking and male fertility and also assesses the impact of non-smoking routes of tobacco consumption on male infertility. It also highlights the evidence that links smoking with male infertility, including newly emerging genetic and epigenetic data, and discusses the clinical implications thereof.

[Association between sperm abnormalities and occupational environment among male consulting for couple infertility]

Alteration of sperm parameters related to occupational exposures is the subject of several studies, often on a case-control approach. The study populations usually comprise men consulting in infertility clinics for couple infertility. The objective of this review is to identify, from these case-control studies, the main occupational factors that may be associated with altered sperm parameters. We selected 13 articles in the PubMed database. Participation in these studies varied from 61 to 2619 subjects, with great methodological heterogeneity, particularly in the characterization of exposure. The main occupations that appear significantly associated with a risk of altered sperm parameters are workmen, painters, farmers, welders, plumbers and technicians. When analysis focuses on occupational exposures, a significant result is reported for solvents, heavy metals, heat, vibrations and non-ionizing radiation. None of the selected studies has found a link with exposure to pesticides.

Activation of Toll like receptor 3 induces spermatogonial stem cell apoptosis

Germ cell apoptosis may be associated with the male infertility. The pathogenesis is to be further understood. Viral infection is one of the causative factors of apoptosis of the body cells. This study aims to investigate the role of activation of Toll like receptor (TLR)3 in the induction of germ cell apoptosis. In this study, spermatogonial stem cells (SSC) were isolated from C57BL/6 mouse testes. The expression of TLR3 on SSC was by RT-qPCR and Western blotting. polyinosinic-polycytidylic acid (Poly I:C) was employed to activate TLR3 on SSCs. The results showed that re-activation by PolyI:C induced SSC apoptosis. Exposure to PolyI:C induced interferon regulatory factor 3 (IRF3) phosphorylation in SSCs. TLR3 and IRF3 formed a complex in the SSCs. The complex of TLR3/IRF3 bound to the promoter of Fas ligand and promoted Fas ligand expression in SSC, and thus induced SSC apoptosis. In conclusion, the results of the present study indicate that activation of TLR3 by PolyI:C induces the SSC apoptosis, which implies that viral infection may interfere with the male germ cell development.

Histomorphometric studies of the effects of Telfairia occidentalis on alcohol-induced gonado-toxicity in male rats

Background

Available evidence suggests that 50% of couples with infertility are male related. Over 40% of these males consume alcohol which has been reported to be a reproductive toxicant causing depletions in the epithelium of seminiferous tubules hence reducing sperm counts and sperm morphology.

Objective

To determine the effects of aqueous leaf extract of Telfairia occidentalis on alcohol-induced cyto-architectural changes in the testis.

Methods

Aqueous leaf extract of Telfairia occidentalis (T. occidentalis) was administered by gastric gavage at a dose of 250 mg/kg and 500 mg/kg body weight daily, while 2 g/kg body weight of ethanol at 30% v/v was administered daily to mature male Sprague–Dawley rats. The experiment was in 2 phases. Phase 1 had groups A₁–F₁ and lasted for 4 weeks while phase 2 had groups A₂–F₂ and lasted 8 weeks. Parameters tested include: testicular histology, relative volume density, sperm parameters, malondialdehyde (MDA), superoxide dismutase (SOD) and reduced glutathione.

Results

In both phases, there were depletions in the seminiferous epithelium, decreased sperm quality and increased MDA and SOD in animals that received alcohol only compared to control. Likewise, a significant increase of seminiferous epithelium of animals that received respective doses of 250 mg/kg and 500 mg/kg of T. occidentalis only compared to control. Animals that received T. occidentalis and alcohol simultaneously had a significant increase in seminiferous epithelium and sperm quality with decreased MDA level.

Conclusion

T. occidentalis attenuated the deleterious effects of alcohol to the cyto-architecture of the testis, protected the seminiferous epithelium, reduced oxidative stress and promoted spermatogenesis.

Antioxidative effects of cerium dioxide nanoparticles ameliorate age-related male infertility: optimistic results in rats and the review of clinical clues for integrative concept of men health and fertility

Background

Male infertility has largely idiopathic, multifactorial origin. Oxidative stress is a major factor that affects spermatogenesis, in particular in aging. Cerium dioxide nanoparticles (CNPs) due to their antioxidative properties are promising to impact on the development of male infertility. The aims of this study were to investigate the effects of CNPs on fertility parameters in 24-month male rats and to overview relevant literature in the field of personalized treatments, predictive diagnosis, and preventive measures for male health and fertility.

Methods

We included 30 24-month-old male rats. After a week of adaptation to the standard diet, the rats were randomly divided into three groups with ten rats in each. Group 1 (controls) received only a standard diet. The rats of group 2 and 3 in adjunct to the standard diet during 10 days received intragastrically 10 % sodium citrate and citrate-coated CNPs in dose 1 mg/kg, respectively. We assessed sex hormones, epididymal sperm parameters and spermatogenesis, ultrasound, and morphological data of rat reproductive organs.

Results

After a 10-day administration of CNPs, we revealed significant decrease of lipid peroxidation product levels in serum and increase of catalase and SOD activity, associated with increase of sperm count (p < 0.001) and improvement in quantitative sperm parameters (motility, viability, and percentage of spermatozoa). We found no significant changes between sperm quantitative parameters in citrate-treated rats and controls and observed age-related decrease of activated Leydig cell number and focal atrophy of the seminiferous tubules. In CNP group, we observed regeneration of seminiferous tubules, increase number and activation of Leydig cells, and 2.5-fold significant increase of serum testosterone. Ultrasound data showed the slight increase of linear measurement and volume of rat testes in CNP group. Review highlights the benefits for predictive diagnosis, preventive measures, and personalized approaches to manage male infertility in the general concept of male health also related to aging.

Conclusion

Citrate-coated 2–5-nm CNPs lead to increase in sex hormones levels, sperm count, and quality, as well as the activation of spermatogenesis in 24-month-old male rats. Nanoceria demonstrated the perspectives to be an effective infertility treatment via reduction of oxidative stress in male reproductive organs, in particular in aging.

Acquired defects in CFTR-dependent β-adrenergic sweat secretion in chronic obstructive pulmonary disease

RATIONALE

Smoking-induced chronic obstructive pulmonary disease (COPD) is associated with acquired systemic cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. Recently, sweat evaporimetry has been shown to efficiently measure β-adrenergic sweat rate and specifically quantify CFTR function in the secretory coil of the sweat gland.

OBJECTIVES

To evaluate the presence and severity of systemic CFTR dysfunction in smoking-related lung disease using sweat evaporimetry to determine CFTR-dependent sweat rate.

METHODS

We recruited a cohort of patients consisting of healthy never smokers (N = 18), healthy smokers (12), COPD smokers (25), and COPD former smokers (12) and measured β-adrenergic sweat secretion rate with evaporative water loss, sweat chloride, and clinical data (spirometry and symptom questionnaires).

MEASUREMENTS AND MAIN RESULTS

β-adrenergic sweat rate was reduced in COPD smokers (41.9 ± 3.4, P < 0.05, ± SEM) and COPD former smokers (39.0 ± 5.4, P < 0.05) compared to healthy controls (53.6 ± 3.4). Similarly, sweat chloride was significantly greater in COPD smokers (32.8 ± 3.3, P < 0.01) and COPD former smokers (37.8 ± 6.0, P < 0.01) vs. healthy controls (19.1 ± 2.5). Univariate analysis revealed a significant association between β-adrenergic sweat rate and female gender (β = 0.26), age (-0.28), FEV1% (0.35), dyspnea (-0.3), and history of smoking (-0.27; each P < 0.05). Stepwise multivariate regression included gender (0.39) and COPD (-0.43) in the final model (R()2 = 0.266, P < 0.0001).

CONCLUSIONS

β-adrenergic sweat rate was significantly reduced in COPD patients, regardless of smoking status, reflecting acquired CFTR dysfunction and abnormal gland secretion in the skin that can persist despite smoking cessation. β-adrenergic sweat rate and sweat chloride are associated with COPD severity and clinical symptoms, supporting the hypothesis that CFTR decrements have a causative role in COPD pathogenesis.

Does cigarette smoking affect seminal fluid parameters? A comparative study

OBJECTIVE

To study the effect of cigarette smoking on seminal fluid parameters, namely; volume, sperm concentration, and motility, as well as morphology, leukocyte infiltration, among males complaining of infertility.

METHODS

Between August 2010 and July 2011, seminal fluid analysis was done for 1438 males who are partners of couples who visited the infertility clinic at Prince Rashid Ben Al Hassan Hospital (PRH) for infertility. The men who fit the inclusion criteria (n=960) were classified into two groups: group a (non-smokers; n=564) and group B (smokers; n=396), which represents 41.25% of the study group. Seminal fluid was collected using masturbation after 3-5 days of abstinence then analyzed for volume, sperm count, sperm concentration, motility and morphology. In order to analyze whether the number of cigarettes smoked per day has an effect on the spermatogram; the smoking men were divided into two subgroups: the heavy smokers (n=266) and non-heavy smokers (n=130).

RESULTS

A total of 960 adult males were enrolled. Their age ranged between 21 and 76 years, 564 were non-smokers with mean age of 36. 45±6.27 (Mean±SD). Three-hundred-and-ninety-six were smokers with a mean age of 34.35±4.25 (Mean±SD). There was a significant effect of smoking on the motility of sperms and the ratios of abnormality (p<0.005). Concentration appeared not to be affected by smoking. Furthermore, the group of heavy smokers were found to have lower sperm concentrations and a higher percentage of abnormal sperms compared to the non-heavy smokers.

CONCLUSION

Cigarette smoking has a deleterious effect on some of the seminal fluid parameters (motility, morphology and leukocyte count) which in turn may result in male subfertility.

The Effects of Smoking and Alcohol Intake on Sperm Quality: Light and Transmission Electron Microscopy Findings

Objective:

To evaluate the effects of alcohol consumption and cigarette smoking on sperm quality using transmission electron microscopy and light microscopy.

Methods:

Semen samples were collected from 62 healthy men. The subjects were classified according to alcohol consumption and smoking status. Semen analysis was performed according to World Health Organization criteria. Transmission electron microscopy was used to examine sperm ultrastructure.

Results:

Heavy smoking (> 20 cigarettes/day) was associated with a decreased sperm count. Moderate/high alcohol consumption (≥15.4 g/day) was associated with an increase in morphologically abnormal sperm. Transmission electron microscopy revealed no effect of smoking on sperm ultrastructure. Alcohol consumption resulted in significant increases in morphologically abnormal nuclei and plasma membranes.

Conclusions:

Heavy smoking was associated with decreased sperm counts and alcohol consumption was associated with increased numbers of morphologically abnormal sperm.

Focus issue on male infertility

Male infertility problems can occur when sperms are limited in number or function. In this paper, we describe the clinical evaluation of male infertility. A detailed history, physical examination, and basic semen analysis are required. In addition, ultrasound, karyotyping, and hormonal studies are needed to determine specific causes of infertility. In addition, the World Health Organization (WHO, 2009) has developed a manual to provide guidance in performing a comprehensive semen analysis. Among the possible reasons for male infertility, nonobstructive azoospermia is the least treatable, because few or no mature sperm may be produced. In many cases, men with nonobstructive azoospermia typically have small-volume testes and elevated FSH. Although treatment may not completely restore the quality of semen from men with subnormal fertility, in some cases a successful pregnancy can still be achieved through assisted reproductive technology.

EFFECT OF LIFESTYLE FACTORS ONINFERTILITY IN MEN

Environmental factors, changes in lifestyle and occupational exposures are responsible for declining human semen quality. We investigated the effects of history of surgery and lifestyle choices on infertility of 271 infertile men and 251 healthy volunteers. The frequency of varicocelectomy was significantly higher in infertile men (2.9%) than in controls (0.4%; P < 0.05). Alcohol use was significantly more common in infertile men (92%) than in controls (80%; P < 0.01). Satisfaction with sexual life was greater in controls (85%) than in infertile men (77%; P < 0.05). Other factors had no effect.

Effects of environmental tobacco smoke in vivo on rhesus monkey semen quality, sperm function, and sperm metabolism

The objective of this study was to use a non-human primate model to examine the effect of environmental tobacco smoke (ETS) in vivo on semen quality, sperm function, and sperm metabolism. Four adult rhesus macaques (Macaca mulatta) were exposed to ETS for six months, and semen samples were collected every week for evaluation. ETS exposure in vivo did not affect semen quality and sperm function. The sperm X:Y chromosome ratio remained unchanged after ETS exposure. The sex ratio of the embryos fertilized by ETS-exposed males was not different from the control male. However, sperm showed changes in metabolome detected by NMR during the ETS exposure. We concluded that with the duration and level of ETS exposure in this study, semen quality and sperm function were not affected, whereas sperm did undergo metabolic changes with ETS exposure in vivo.

A case-control study of risk factors for male infertility in Nigeria

AIM

To evaluate the association between selected potential socio-demographic and behavioral risk factors and infertility in Nigerian men.

METHODS

There were two groups in this study. One group consisted of 150 men with proven male infertility, and the other consisted of 150 fertile men with normal semen parameters. Both were matched for age, place of residence and key socio-demographic variables. They were compared for sexual history, past medical and surgical history, past exposures to sexually transmitted infections and treatment, past and current use of drugs as well as smoking and alcohol intake history.

RESULTS

Infertile men were significantly more likely than fertile men to report having experienced penile discharge, painful micturition and genital ulcers, less likely to seek treatment for these symptoms and more likely to seek treatment with informal sector providers. Multivariate analysis showed that male infertility was significantly associated with bacteria in semen cultures, self-reporting of previous use of traditional medications and moderate to heavy alcohol intake, but not with smoking and occupational types.

CONCLUSION

INFERTILITY is associated with various proxies of sexually transmitted infections (STIs) and poor healthcare-seeking behavior for STIs in Nigerian men.

Influence of cigarette smoking on spermatozoa via seminal plasma

Numerous investigations have been conducted on the relationship between cigarette smoking and male infertility, however, the exact molecular mechanisms are not well understood in most of the cases. Few studies have indicated the direct effect of seminal plasma (SP) [in different dilutions with phosphate buffer solution (PBS)] from smokers (SM) on the sperm functional parameters from nonsmokers (non-SM). The aim of this study was to provide evidence that cigarette smoking affects male fertility via altering the sperm quality. Our results indicated that exposure of spermatozoa from the non-SM to the SP from the SM yielded a significant reduction in the sperm motility and acrosome reaction and an elevation in the amount of malondialdehyde (MDA), in a certain time course. Exposure of spermatozoa from the SM to the SP from the non-SM or with PBS resulted in the nonsignificant improvement in the altered sperm functional parameters indicating removal of SM's SP and then subsequent reconstitution with physiological media could be of clinical significance in the various assisted reproductive technologies applied for SM. However, the detrimental effect of SM's SP on non-SM's spermatozoa was prominent. In addition, as spermatozoa in SM's SP are susceptible to peroxidative damages, men with such cells who wish to have children should especially benefit from quitting smoking.

The Use of Semen Parameters to Identify the Subfertile Male in the General Population

AIMS

To present a structured review of the literature published on semen parameters and in vivo fertility potential and to establish fertility/subfertility thresholds for sperm morphology using Tygerberg strict criteria, sperm concentration, and sperm motility.

METHOD

The published literature comparing fertile and subfertile populations between 1983 and 2002 was reviewed.

RESULTS

A total of 265 articles were identified by the sourcing methodology, but only four articles provided data that could be tabulated and analyzed. Using receiver-operating characteristics curves, morphology proved to be the best predictor of subfertility in 2 of the 4 articles, with concentration and motility also showing good predictive power. The thresholds calculated ranged between 4 and 10% for morphology, between 13.5 x 10(6)/ml and 34 x 10(6)/ml for concentration, and between 32 and 52% for motility. A second set of much lower thresholds was calculated in three of the articles using either a 15 or 50% prevalence of subfertility in the population or the tenth percentile of the fertile population. The adjusted thresholds were between 3 and 5% for morphology, between 9 x 10(6)/ml and 20 x 10(6)/ml for concentration, and between 20 and 30% for motility.

CONCLUSIONS

Because these lower thresholds have a much higher positive predictive value, we suggest that thresholds of <5% normal sperm morphology, a concentration <15 x 10(6)/ml, and a motility <30% should be used to identify the subfertile male. The lower threshold for morphology also fits in vitro fertilization and intrauterine insemination data calculated previously. Using the parameters in combination increases the clinical value of semen analysis.

The Effect of Alcohol, Tobacco, and Aspirin Consumption on Seminal Quality among Healthy Young Men

In this study, the authors examined the effects of alcohol, tobacco, and drug use on plasma testosterone and seminal parameters (in accordance with the World Health Organization's standards) in healthy Argentine medical students (n = 34). Some alterations in seminal parameters were detected in 19 (56%) subjects. Alcohol and tobacco use were correlated significantly, p = 0.005; subjects who used these substances exhibited a nonsignificant reduction in sperm concentration, motility, viability, and normal morphology. There was a significant decrease in sperm motility among students who used moderate amounts of aspirin (i.e., > or = 500 mg/wk). The authors concluded that alcohol, tobacco, and aspirin use could have had detrimental effects on seminal parameters and that men who wish to procreate should be warned of such effects. Doses, exposure time, and interactions with other variables deserve additional study.

Effects of alcohol and cigarette consumption on human seminal quality

OBJECTIVE

To evaluate the effects of alcohol or cigarette consumption on seminal parameters in a large population of men attending an andrology laboratory.

DESIGN

Analysis of ten years of data (1990-1999).

SETTING

Andrology and Reproduction Laboratory (Córdoba, Argentina).

PATIENT(S)

Patients (3,976) were grouped according to nonsmokers; <==20 cigarettes/day; >20 cigarettes/day; nonalcohol consumers; <==500 mL of wine ( approximately 52 g of ethanol) or equivalent/day; and >500 mL of wine or equivalent/day. Patients who drank alcohol and smoked were also considered.

INTERVENTION(S)

A questionnaire was voluntarily filled out by patients. It provided data on drug consumption and genitourinary diseases.

MAIN OUTCOME MEASURE(S)

Seminal volume, sperm concentration, motility, viability, and morphology.

RESULTS

No statistical differences in seminal parameters were found between the degrees of alcohol or tobacco consumption; so, independently of the degree of consumption patients were considered as smokers or alcohol consumers.

CONCLUSION(S)

Alcohol or cigarette consumption did not alter the seminal parameters. Nevertheless, when the patients with these two habits were compared to those without these habits, a significant reduction in seminal volume, sperm concentration, percentage of motile spermatozoa, and a significant increase of the nonmotile viable gametes were detected. The synergic or additive effect of these two toxic habits is discussed.

Low birth weight in relation to parental occupations—a population-based registry in Singapore (1994–1998)

OBJECTIVES

To study the association between parental occupation and low birth weight (LBW) in infants born in Singapore between 1994 and 1998. Other factors that may be related to LBW were also investigated.

METHODS

A retrospective study. Information was obtained from the Singapore National Registry of Births and Deaths on parental occupations for live births between 1 January 1994 to 31 December 1998. Parental date of birth, ethnic group, and highest educational qualification were also obtained. The associations between these factors and the occurrence of LBW was assessed using descriptive statistics and logistic regression analysis.

RESULTS

A total 208,360 live births were studied. Analyses were restricted to singleton births > or =37th week gestation (total of 189,064). No significant differences in LBW risk were found for the different maternal occupational groups, compared with a referent group ("legislators, senior officers, and managers"). However, fathers who were "not working" (OR=2.04; 1.57-2.65), "not classifiable by occupation" (OR=1.34; 1.09-1.65), and "cleaners, laborers, and related workers" (OR=1.32; 1.12-1.55) had the highest risk of LBW infants when compared with "legislators, senior officers, and managers," after adjustment for maternal occupation, ethnic group, educational level and age, paternal educational level, infant gestational age, sex, and birth order.

CONCLUSION

Certain paternal occupational groups appear to be associated with a higher risk of having LBW infants. This may be linked to socioeconomic status and possible work-related factors. Future studies of pregnancy outcomes should not ignore the potential contributions of fathers.

Negative lifestyle is associated with a significant reduction in fecundity

OBJECTIVE

To evaluate the association patterns and quantify the effects of lifestyle on time to pregnancy (TTP).

DESIGN

Observational study.

SETTING

Teaching hospitals in Hull, United Kingdom.

PATIENT(S)

Two thousand and one hundred twelve consecutive pregnant women.

INTERVENTION(S)

A questionnaire inquiring about TTP, contraceptive use, pregnancy planning, previous subfertility/pregnancies, age, and lifestyle characteristics of either partner.

MAIN OUTCOME MEASURE(S)

We compared TTP, conception rates, and relative risk of subfecundity between subgroups with different lifestyle characteristics.

RESULT(S)

We found that TTP was significantly longer if the woman or partner smoked >15 cigarettes/day (P<.001 and.04, respectively), the partner consumed >20 alcohol units/week (P<.001), the woman's body mass index was >25 kg/m(2) (P<.001), their coffee and/or tea intake was >6 cups/day (P=.04), or if they were socially deprived (P<.001). Each of these effects remained unchanged after adjusting for the potential confounders. The relative-risks of subfecundity with each of these variables ranged between 1.4 to 1.9 (1.4 to 3.6 after adjustment). The effects of coital frequency and recreational drug use were insignificant. Couples who had >4 negative lifestyle variables had a sevenfold longer TTP; their conception probabilities fell by 60%, and they were 7.3-fold more likely to be subfecund than those without negative variables.

CONCLUSION(S)

Lifestyle has a significant and cumulative impact on fecundity. Dose-dependent effects occur with smoking, alcohol, and tea/coffee consumption. Appropriate counseling could result in substantial reductions in the referrals for fertility investigations and treatments.

Male smokers have a decreased success rate for in vitro fertilization and intracytoplasmic sperm injection

OBJECTIVE

Smoking by one or both partners can adversely affect IVF outcome. We investigated whether smoking may also play a role in the success rate of intracytoplasmic sperm injection (ICSI), in which initial steps of fertilization are bypassed.

DESIGN

Three hundred one couples (ICSI: 153, IVF: 148) participated in 415 treatment cycles (ICSI: 202, IVF: 213). One hundred thirty-nine men were habitual smokers (ICSI: 71, IVF: 68). Seventy-seven women were smokers (ICSI: 41, IVF: 36). Multiple nominal regression analyses of various steps of assisted reproduction included smoking status, age, semen parameters, and number of embryos transferred.

SETTINGS

Reproductive and andrology unit of the university.

PATIENT(S)

Three hundred one couples seeking fertility treatment.

INTERVENTION(S)

Assisted reproduction by in vitro fertilization (IVF) or ICSI.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy.

RESULT(S)

Intracytoplasmic sperm injection success (clinical pregnancy) in women with smoking male partners was 22% and was 38% with nonsmoking partners. Similar results were seen for IVF, with 18% vs. 32%. Multinominal logistic regression analysis revealed smoking in men to be a significant predictor of ICSI outcome, along with female age and the number of embryos transferred, whereas clinical pregnancies after IVF were dependent on smoking in men, number of embryos transferred, sperm motility, and female age. Female smoking influenced the number of oocytes retrieved and the fertilization rate of oocytes in IVF but not in ICSI. The odds ratio for failure of ICSI for male smokers in comparison to male nonsmokers was 2.95 (IVF: 2.65).

CONCLUSION(S)

Smoking by males decreases the success rates of assisted reproduction procedures, not only in IVF, but also in ICSI. Apart from putative adverse effects during fertilization, altered DNA in spermatozoa might hamper development of the embryo.

Effect of male age on fertility: evidence for the decline in male fertility with increasing age

OBJECTIVE

To evaluate the effect of men's age on time to pregnancy (TTP) using age at the onset of pregnancy attempts, adjusting for the confounding effects of women's age, coital frequency, and life-style characteristics.

DESIGN

Observational study.

SETTINGS

Teaching hospital in Hull, United Kingdom.

PATIENT(S)

Two thousand one hundred twelve consecutive pregnant women.

INTERVENTION(S)

A questionnaire inquiring about TTP, contraceptive use, pregnancy planning, previous subfertility, previous pregnancies, age, and individual life-style characteristics of both partners.

MAIN OUTCOME MEASURE(S)

Time to pregnancy, conception rates, and relative risk of subfecundity for men and women's age groups.

RESULTS

As with women's age, increasing men's age was associated with significantly rising TTP and declining conception rates. A fivefold increase in TTP occurred with men's age >45 years. Relative to men <25 years old, those >45 years were 4.6-fold and 12.5-fold more likely to have had TTP of >1 or >2 years. Restricting the analysis to partners of young women revealed similar effects of increasing men's age. Women >35 years were 2.2-fold more likely to be subfertile than women <25 years. The results were comparable, whether age at conception or at the onset of pregnancy attempts was analyzed, and they remained unchanged after adjustment for the confounding factors.

CONCLUSION(S)

Evidence for and quantification of the decline in men's fertility with increasing age is provided.

Semen quality of male smokers and nonsmokers in infertile couples

OBJECTIVE

To investigate the effect of cigarette smoking on main sperm variables.

DESIGN

Cohort study.

SETTING

Men attending the andrology laboratory in the context of infertility investigation in the couple.

PATIENT(S)

Eight hundred thirty-nine smokers and 1,266 non-smokers were enrolled; 655 smokers and 1,131 nonsmokers fulfilled the inclusion criteria and were compared. Standard clinical analysis of semen.

RESULT(S)

Cigarette smoking was associated with a significant decrease in sperm density (-15.3%), total sperm count (-17.5%), total number of motile sperm (-16.6%), and citrate concentration (-22.4%). The percentage of normal forms was significantly reduced in smokers, and sperm vitality, ejaculate volume, and fructose concentration were slightly but nonsignificantly affected.

CONCLUSION(S)

Cigarette smoking is associated with reduced semen quality.

Biomarkers for male reproductive health hazards: are they available?

This review aims to give an overview of some of the biomarkers that have been used for the monitoring of human exposure to xenobiotics as well as to provide a summary of some of the recent epidemiological studies on male reproductive health of exposure to environmental and occupational toxicants. Possible molecular mechanisms on seminal quality change are also suggested. Studies using various biomarkers have no doubt enabled us to better characterize the effect of environmental pollutants on the male reproductive system. However, the sensitivity and specificity of these biomarkers have not been comprehensively validated. Furthermore, many epidemiological findings are difficult to replicate owing to the inherited methodological problems of male reproductive health investigations, such as the small number of study subjects, low compliance rate, substantial intra-individual variability in semen parameters, measurement techniques and misclassifications based on single assay. Oxidative damage, in particular DNA-damage caused by free radicals, generated either by xenobiotics, or endogenously, is now thought to be a key molecular mechanism associated with semen quality and sperm function. Laboratory studies and epidemiological findings have suggested that the male reproductive system is susceptible to reactive oxygen species (ROS). On the other hand, there is so far no single all-encompassing biomarker of reproductive capacity in men. A panel of biomarkers with specific goals should be considered. Collaborative multidisciplinary studies are also needed to overcome some of the issues mentioned here.

Occupational risk for male infertility: a case-control study of 218 infertile and 227 fertile men

The aim of the study was to determine if certain occupations pose an increased risk for infertility (of no known cause) among a group of infertile men compared with a group of fertile men. A total of 640 consecutive men whose spouses were unable to conceive were recruited from an infertility clinic. Of these, 218 men (cases) were found to have no known cause for their infertility. A total of 227 men whose spouses were pregnant at the time of the study were recruited as controls. The Singapore Standard Occupational Classification was used to code the subjects' occupations. Semen parameters (density, total sperm counts, motility, viability, and normal morphology) in all of the cases were significantly poorer than those in the controls. The risk for infertility is associated with smoking adjusted odds ratio (OR) 2.85 and 95% confidence interval (CI) 1.91 to 4.24. Work, independently, is not a risk factor for infertility. Engineering technicians (adjusted OR, 2.75; 95% CI, 1.36 to 5.54), finance analysts (adjusted OR, 4.66; 95% CI, 1.90 to 11.40), corporate and computing managers (adjusted OR, 2.49; 95% CI, 1.04 to 5.98), and teachers (adjusted OR, 7.72; 95% CI, 1.86 to 32.10) were at a greater risk of infertility compared with "services and clerical workers." Using services and clerical workers as a reference group, certain occupations are at a higher risk for infertility. Higher work demands and possible electromagnetic field exposure could be contributory factors for infertility.

The Chinese experience of male infertility

The purpose of this study was to describe the lived experiences of Chinese men who were diagnosed as infertile. Thirty men who had experienced infertility were interviewed in or near the clinic of a large general teaching hospital located in Taiwan. The interviews were analyzed using content analysis. Five categories were generated from the interview data: emotional response after hearing the diagnosis; seeking possible explanations for the diagnosis; using alternative treatments other than those of Western medicine; stressfrom the discovery of the infertility secret by family, relatives, and friends; and grief for discontinuation of the family heritage. Men in this study described infertility as a frustrating and stressful experience. Findings from this study can add to the knowledge base on infertility and contribute to recommendations for improving the ways that health professionals guide, counsel, and support men who are infertile.