Influence of body mass index and waist-hip ratio on male semen parameters in infertile men in the real world: a retrospective study

Exploring the impact of lipid stress on sperm cytoskeleton: insights and prospects

The decline in male fertility correlates with the global rise in obesity and dyslipidaemia, representing significant public health challenges. High-fat diets induce metabolic alterations, including hypercholesterolaemia, hepatic steatosis and atherosclerosis, with detrimental effects on testicular function. Testicular tissue, critically dependent on lipids for steroidogenesis, is particularly vulnerable to these metabolic disruptions. Excessive lipid accumulation within the testes, including cholesterol, triglycerides and specific fatty acids, disrupts essential sperm production processes such as membrane formation, maturation, energy metabolism and cell signalling. This leads to apoptosis, impaired spermatogenesis, and abnormal sperm morphology and function, ultimately compromising male fertility. During spermiogenesis, round spermatids undergo extensive reorganization, including the formation of the acrosome, manchette and specialized filamentous structures, which are essential for defining the final sperm cell shape. In this Perspective, we examine the impact of high-fat diets on the cytoskeleton of spermatogenic cells and its consequences to identify the mechanisms underlying male infertility associated with dyslipidaemia. Understanding these processes may facilitate the development of therapeutic strategies, such as dietary interventions or natural product supplementation, that aim to address infertility in men with obesity and hypercholesterolaemia. The investigation of cytoskeleton response to lipid stress extends beyond male reproduction, offering insights with broader implications.

Influence of Body Mass Index (BMI) and Waist-Hip Ratio (WHR) on Selected Semen Parameters

Because male obesity may result in reproductive failure, we aimed to examine the possible links among body mass index (BMI), the waist-hip ratio (WHR), and basic semen parameters, the oxidation-reduction potential of semen, the total antioxidant capacity of seminal plasma, the ability of sperm to bind hyaluronic acid, and sperm DNA fragmentation (SDF). This study was performed on semen (n = 543) collected from volunteers classified as follows: normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25.0-29.9 kg/m2), obese (BMI ≥ 30.0 kg/m2), with a normal WHR (<1) or abnormal WHR (≥1). No significant differences in standard semen parameters were found between men with a normal BMI and those with overweight/obesity. However, compared with overweight men, obese men had a higher SDF index prevalence and risk for an SDF index > 20%. Compared with men with WHR < 1, those with WHR ≥ 1 had significantly lower sperm motility, morphology, and vitality and an increased SDF index, prevalence and risk for an SDF index > 20%. In conclusion, abnormal WHR had a greater negative impact on conventional semen parameters than abnormal BMI. Both BMI ≥ 30.0 and WHR ≥ 1 negatively influenced sperm chromatin integrity only. Obesity is a potential risk factor for sperm DNA damage.

Male infertility and obesity

PURPOSE OF REVIEW

The increasing rate of obesity is having an adverse impact on male reproduction.

RECENT FINDINGS

The negative effect of reactive oxygen species on male reproductive tissues and the age of onset of obesity are new areas of research on male infertility.

SUMMARY

This review highlights how obesity impairs male reproduction through complex mechanisms, including metabolic syndrome, lipotoxicity, sexual dysfunction, hormonal and adipokine alterations as well as epigenetic changes, and how new management strategies may improve the reproductive health of men throughout life.

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.

Obesity and Male Infertility: True, True, and Unrelated?

While the prevalence of obesity has rapidly increased worldwide, there has also been a notable decline in semen parameters over the last several decades. While obesity can negatively impact reproductive hormones, many studies have sought a link between rising obesity and decreased male fertility potential. Nonetheless, few data support a direct link between the two. The focus on obesity as a causative factor in male infertility can potentially result in patient harm through delayed fertility treatment and missed diagnoses. This review investigates the associations between obesity and male infertility and why a potential direct link has been elusive and may not exist. Additionally, indirect mechanisms that may link the two will be reviewed and treatment options for obese infertile men presenting for evaluation will briefly be discussed.

Association between mitochondrial DNA genotype and sperm motility in humans

The relationship between genetic alterations in mitochondrial DNA (mtDNA) and progressive motility (PR) and rapid progressive motility (grade A) of ejaculated human spermatozoa remains unclear. In this study, we explored the association between human mtDNA genotype and sperm PR and grade A by analyzing mtDNA copy number, loci, haplogroup, rearrangement, deletions, and duplications and sperm motility parameters. Human sperm mtDNA copy number, loci and haplogroups were not associated with human sperm motility PR or A grade. However, the cumulative frequency of human sperm mtDNA rearrangements (including deletions and duplications) in participants with high PR and grade A ratio was higher than in participants with low PR and grade A ratio. Additional studies are needed to understand the relationship between mtDNA genotypes, including deletions and duplications, and human sperm motility.