A ripple effect? The impact of obesity on sperm quality and function

Infertility affects approximately 15% of couples trying to conceive. Male-related causes account for roughly 50% of cases, with obesity emerging as a possible significant factor. Obesity, defined as a body mass index of 30.0 or higher, has become a widespread epidemic associated with numerous health issues, including a decrease of fertility. This review discusses the relationship between obesity and male infertility, particularly focusing on sperm quality and function. An overview of the literature suggests that obesity may influence the male reproductive system via disruptions in hormonal profiles, oxidative stress, and inflammation, leading to changes in sperm parameters. Several studies have discussed if obesity causes a decrease in sperm concentration, motility, and normal morphology, so far without a consensus being reached. However, available evidence suggests an impairment of sperm function in obese men, due to an increase in DNA damage and oxidative stress, impaired mitochondrial function and acrosome reaction in response to progesterone. Finally, the relationship between obesity and assisted reproductive technologies outcomes remains debatable, with conflicting evidence regarding the influence on fertilisation, pregnancy, and live birth rates. Therefore, the actual impact of obesity on human spermatozoa still needs to be clarified, due to the multiple factors potentially in play.

Signatures of metabolic diseases on spermatogenesis and testicular metabolism

Diets leading to caloric overload are linked to metabolic disorders and reproductive function impairment. Metabolic and hormonal abnormalities stand out as defining features of metabolic disorders, and substantially affect the functionality of the testis. Metabolic disorders induce testicular metabolic dysfunction, chronic inflammation and oxidative stress. The disruption of gastrointestinal, pancreatic, adipose tissue and testicular hormonal regulation induced by metabolic disorders can also contribute to a state of compromised fertility. In this Review, we will delve into the effects of high-fat diets and metabolic disorders on testicular metabolism and spermatogenesis, which are crucial elements for male reproductive function. Moreover, metabolic disorders have been shown to influence the epigenome of male gametes and might have a potential role in transmitting phenotype traits across generations. However, the existing evidence strongly underscores the unmet need to understand the mechanisms responsible for transgenerational paternal inheritance of male reproductive function impairment related to metabolic disorders. This knowledge could be useful for developing targeted interventions to prevent, counteract, and most of all break the perpetuation chain of male reproductive dysfunction associated with metabolic disorders across generations.

Insights into the implication of obesity in hypogonadism among adolescent boys

OBJECTIVES

This research aimed at uncovering the mechanisms behind obesity-related hypogonadism in adolescent boys and to investigate the association between anthropometric characteristics and testicular functions of these boys.

METHODS

This study included 60 adolescent boys (12-18 years) with exogenous obesity (BMI≥95th percentile) and 30 age matched lean controls (BMI=15th-85th percentile). Full clinical examination, anthropometric measurements and pubertal assessment were performed. Laboratory investigations included hemoglobin, hematocrit, lipid panel, LH, FSH, free and total testosterone, inhibin B and estradiol.

RESULTS

The results indicated the presence of positive family history of obesity in 85% of obese boys vs. 40% of the lean counterparts. Concerning SBP of obese boys, 7% were hypertensive (95th percentile), 25% were prehypertensive (between 90th and 95th percentiles) while, DBP findings showed that 33% are hypertensive and 33% are prehypertensive. Meanwhile, 13.3% of lean controls were prehypertensive. Anthropometric measurements and lipid profile values revealed a significant difference between obese and lean boys. Compared to obese boys the normal weight boys had higher levels of free testosterone (21.15 ± 2.90 pg/mL vs. 11.38 ± 3.96 pg/mL, p<0.001), total testosterone (10.59 ± 6.63 ng/dL vs. 3.23 ± 1.70 ng/dL, p<0.001), FSH (7.33 ± 3.75 mIU/mL vs. 5.63 ± 3.96 mIU/mL, p=0.026) and inhibin B (83.28 ± 27.66 pg/mL vs. 62.90 ± 17.85 pg/mL, p=0.001) and they registered lower level of estradiol (18.48 ± 7.33 pg/mL vs. 40.20 ± 7.91 pg/mL, p<0.001). In obese boys, BMI SDS significantly correlated with lipid profile and estradiol whereas, it showed significant negative correlation with LH, free and total testosterone and inhibin B. Penile length significantly correlated with LH while it revealed significant negative correlation with cholesterol.

CONCLUSIONS

This study evidenced a close association between obesity and hypogonadism in adolescent boys which could be due to the increased estradiol level and decreased T/E2 ratio.

Enterotypes in asthenospermia patients with obesity

The essence of enterotypes is stratifying the entire human gut microbiome, which modulates the association between diet and disease risk. A study was designed at the Center of Reproductive Medicine, Shengjing Hospital of China Medical University and Jinghua Hospital of Shenyang. Prevotella and Bacteroides were analyzed in 407 samples of stool, including 178 men with enterotype B (61 normal, 117 overweight/obese) and 229 men with enterotype P (74 normal, 155 overweight/obese). The ratio between Prevotella and Bacteroides abundance, P/B, was used as a simplified way to distinguish the predominant enterotype. In enterotype P group (P/B ≥ 0.01), obesity was a risk factor for a reduced rate of forward progressive sperm motility (odds ratio [OR] 3.350; 95% confidence interval [CI] 1.881-5.966; P < 0.001), and a reduced rate of total sperm motility (OR 4.298; 95% CI 2.365-7.809; P < 0.001). Obesity was also an independent risk factor (OR 3.131; 95% CI 1.749-5.607; P < 0.001) after adjusting follicle-stimulating hormone. In enterotype P, body mass index, as a diagnostic indicator of a reduced rate of forward progressive sperm motility and a decreased rate of decreased total sperm motility, had AUC values of 0.627 (P = 0.001) and 0.675 (P < 0.0001), respectively, which were significantly higher than the predicted values in all patients. However, in enterotype B group (P < 0.01), obesity was not a risk factor for asthenospermia, where no significant difference between obesity and sperm quality parameters was observed. This study is tried to introduce enterotypes as a population-based individualized classification index to investigate the correlation between BMI and asthenospermia. In our study, overweight/obese men with enterotype P were found to have poorer sperm quality. however, sperm quality was not associated with overweight/obese in men with enterotype B. Thereof, BMI is a risk factor for asthenospermia only in men with enterotype P, but not in men with enterotype B.

Obesity and reproduction: a committee opinion

The purpose of this American Society for Reproductive Medicine Practice Committee report is to provide clinicians with principles and strategies for the evaluation and treatment of couples with infertility associated with obesity. This revised document replaces the Practice Committee document titled "Obesity and reproduction: an educational bulletin" last published in 2015 (Fertil Steril 2015;104:1116-26).

Does obesity based on body mass index affect semen quality?-A meta-analysis and systematic review from the general population rather than the infertile population

Whether obesity affects the quality of semen has become the focus of research. However, there are some deficiencies in the past research, because the vast majority of known infertile patients were included in the study samples. Taking infertile men as the research object to analyse the impact of obesity on semen quality, which cannot accurately prove that the impact on semen quality is caused by obesity, because the impact on semen quality may also be caused by other factors. Therefore, we selected ordinary obese men rather than infertile patients to conduct a systematic review and meta-analysis of the effects of obesity on semen parameters. The results showed that obesity had no effect on sperm concentration (SMD: -0.15, 95% CI: -0.32 ~ 0.02, p = .088) and percentage of normal sperm morphology (SMD: -0.17, 95% CI: -0.66 ~ 0.32, p = .487), but decreased semen volume (SMD: -0.32, 95% CI: -0.52 ~ -0.12, p = .002), total sperm number (SMD: -0.77, 95% CI: -1.31 ~ -0.23, p = .005), percentage of forward progression (SMD: -0.95, 95% CI: -1.7 ~ -0.19, p = .014) and percentage of viability (SMD: -0.812, 95% CI: -1.532 ~ -0.093, p = .027). Therefore, obesity affects semen quality to a certain extent, and maintaining normal weight may be one of the effective ways to improve male fertility.

Male adiposity, sperm parameters and reproductive hormones: An updated systematic review and collaborative meta-analysis

The present updated systematic review and meta-analysis aims to summarize the evidence from published studies with low risk for any important bias (based on methodological quality assessment) investigating the potential associations of adiposity with sperm quality and reproductive hormones. We conducted a systematic search of the literature published in MEDLINE-PubMed and EMBASE through June 2019. Based on the criteria in our review, 169 eligible publications were used for data abstraction. Finally, 60 articles were included in the qualitative analysis and 28 in the quantitative analysis. Our systematic review results indicated that overweight and/or obesity were associated with low semen quality parameters (i.e., semen volume, sperm count and concentration, sperm vitality and normal morphology) and some specific reproductive hormones (e.g., inhibin B, total testosterone and sex hormone-binding globulin). Overweight and/or obesity were also positively associated with high estradiol concentrations. Meta-analysis indicated that overweight and/or obesity categories were associated with lower sperm quality (i.e., semen volume, sperm count and concentration, sperm vitality, total motility and normal morphology), and underweight category was likewise associated with low sperm normal morphology. In conclusion, our results suggest that maintaining a healthy body weight is important for increasing sperm quality parameters and potentially male fertility.

Metabolic diseases affect male reproduction and induce signatures in gametes that may compromise the offspring health

The most prevalent diseases worldwide are non-communicable such as obesity and type 2 diabetes. Noteworthy, the prevalence of obesity and type 2 diabetes is expected to steadily increase in the next decades, mostly fueled by bad feeding habits, stress, and sedentarism. The reproductive function of individuals is severely affected by abnormal metabolic environments, both at mechanical and biochemical levels. Along with mechanical dysfunctions, and decreased sperm quality (promoted both directly and indirectly by metabolic abnormalities), several studies have already reported the potentially harmful effects of metabolic disorders in the genetic and epigenetic cargo of spermatozoa, and the epigenetic inheritance of molecular signatures induced by metabolic profile (paternal diet, obesity, and diabetes). The inheritance of epigenetic factors towards the development of metabolic abnormalities means that more people in reproductive age can potentially suffer from these disorders and for longer periods. In its turn, these individuals can also transmit this (epi)genetic information to future generations, creating a vicious cycle. In this review, we collect the reported harmful effects related to acquired metabolic disorders and diet in sperm parameters and male reproductive potential. Besides, we will discuss the novel findings regarding paternal epigenetic inheritance, particularly the ones induced by paternal diet rich in fats, obesity, and type 2 diabetes. We analyze the data attained with in vitro and animal models as well as in long-term transgenerational population studies. Although the findings on this topic are very recent, epigenetic inheritance of metabolic disease has a huge societal impact, which may be crucial to tackle the 'fat epidemic' efficiently.

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.

Dietary trans and saturated fatty acids effects on semen quality, hormonal levels and expression of genes related to steroid metabolism in mouse adipose tissue

Our objectives were to assess sperm alteration and adipose tissue (AT) genes expression related to steroid metabolism subsequent to fatty acids consumption. Twenty-nine mature male mice were divided into: fat diet (FD; n = 15) and the control group (n = 14). FD group was fed with low level of trans and saturated fatty acids source for 60 days. Sperm parameters, levels of hormones and the mRNA abundance of the target genes in AT were assessed. The sperm concentration, total and progressive motilities were lower in FD group compared to that of control (p < 0.01). Blood estradiol levels increased in FD (p < 0.001), whereas no significant difference was observed in testosterone. The mRNA levels of StAR, CYP11A1, CYP17A1, 17βHSD7 and 17βHSD12 in AT of FD were higher than those of the control (p < 0.05). In contrast, mRNA level of Cyp19a1 in FD was significantly (p < 0.05) lower than that of control. 17βHSD12 and 17βHSD7 (as oestrogenic genes) increased, while 17βHSD5 and 17βHSD3 (as androgenic genes) remained unchanged, indicating that dietary trans/saturated fatty acids affect AT genes expression. Probably, sperm parameters were altered by increment of expression level of genes involved in oestrogenic metabolism rather than those engaged in androgenic metabolism after fatty acids consumption.

Pubertal Status and Gonadal Functions in Obese Boys with Fatty Liver

BACKGROUND

In adult studies, obese subjects with nonalcoholic fatty liver disease (NAFLD) have been shown to have poor sperm quality, and lower testosterone and luteinizing hormone levels. The aim of this study was to investigate the pubertal status and gonadal functions in obese boys with NAFLD.

MATERIALS AND METHODS

The study included 119 obese and 78 nonobese age-matched adolescents. The obese boys were separated into two groups based on the presence (NAFLD group) or absence of liver steatosis with high transaminases (non-NAFLD group). The levels of serum AMH (anti-Mullerian hormone), inhibin B, gonadotropins, total testosterone, lipids, high-sensitivity C-reactive protein, fasting glucose, insulin levels, and aortic intima media thickness were measured in all subjects.

RESULTS

Of the total 197 children, 174 had reached puberty. There were no significant differences between the groups in respect of testicular sizes and the prevalence of pubertal status among the groups (84.3% of NAFLD vs. 70.6% of non-NAFLD vs. 98.7% of control subjects). No significant differences were found in respect of gonadotropins and AMH levels. Total testosterone levels in the NAFLD group were significantly lower than those of the non-NAFLD obese group (P < 0.001) and the control group (P < 0.001). Inhibin B levels were also significantly lower in all (NAFLD and non-NAFLD) obese groups compared to the control group (P = 0.008).

CONCLUSIONS

The results of the study demonstrated that diminished testosterone and inhibin B levels occur in pubertal obese boys with NAFLD. No significant differences were detected according to pubertal status, AMH levels, and testicular volumes in the age-matched groups.

Metabolic Syndrome and Male Fertility

Metabolic syndrome (MetS) represents a cluster of conditions that have a negative impact on human health overall. Its prevalence has been rapidly increasing worldwide and has coincided with a global decrease in birth rates and fertility potential. This review aims to address this observation through studying the relationship between MetS and male reproductive health. The effects of obesity, dyslipidemia, hypertension, and insulin resistance on male fertility were examined and supporting evidence explaining the pathophysiology of sperm dysfunction with each MetS component were described. Adopting a healthy lifestyle appears to be the single most important intervention to prevent the unwanted effects of MetS on men's health and fertility. Further studies addressing the components of MetS and their impact on male reproduction are required to enhance our understanding of the underlying pathophysiology and to propose new methods for therapeutic intervention.

Reactive oxygen species and male reproductive hormones

Reports of the increasing incidence of male infertility paired with decreasing semen quality have triggered studies on the effects of lifestyle and environmental factors on the male reproductive potential. There are numerous exogenous and endogenous factors that are able to induce excessive production of reactive oxygen species (ROS) beyond that of cellular antioxidant capacity, thus causing oxidative stress. In turn, oxidative stress negatively affects male reproductive functions and may induce infertility either directly or indirectly by affecting the hypothalamus-pituitary-gonadal (HPG) axis and/or disrupting its crosstalk with other hormonal axes. This review discusses the important exogenous and endogenous factors leading to the generation of ROS in different parts of the male reproductive tract. It also highlights the negative impact of oxidative stress on the regulation and cross-talk between the reproductive hormones. It further describes the mechanism of ROS-induced derangement of male reproductive hormonal profiles that could ultimately lead to male infertility. An understanding of the disruptive effects of ROS on male reproductive hormones would encourage further investigations directed towards the prevention of ROS-mediated hormonal imbalances, which in turn could help in the management of male infertility.

The complex association between metabolic syndrome and male hypogonadism

BACKGROUND

The complex association between metabolic syndrome (MetS) and male hypogonadism is well established. A number of observational studies show that low testosterone is associated with insulin resistance and an increased risk for diabetes mellitus and MetS in men.

AIMS

To elucidate the association between MetS and male hypogonadism, present epidemiological data on the co-existence of the two comorbidities, enlighten the underlying pathophysiology and appraise the effects of testosterone supplementation therapy (TTh) and lifestyle modifications on MetS and body composition in men.

MATERIALS AND METHODS

Systematic search to PubMed and Medline databases for publications reporting data on association between MetS and male hypogonadism.

RESULTS

Both MetS and male hypogonadism have a high prevalence in the general population and are frequently co-existing e.g. in males with diabetes. Accumulating evidence from animal and human studies suggests that MetS is involved in the pathogenesis of hypogonadism in males as well as the other way around. On the other hand, there is evidence for a favorable effect of testosterone supplementation in testosterone deficient men with MetS and/or diabetes mellitus.

CONCLUSIONS

Studies with superior methodological characteristics are needed in order to establish a role for testosterone supplementation in men with MetS and/or diabetes mellitus.

Effects of Chronic Musculoskeletal Pain on Fertility Potential in Lean and Overweight Male Patients

Both chronic pain and obesity are known to affect reproductive hormone profiles in male patients. However, the effect of these conditions, alone or in combination, on male fertility potential has received less attention. 20 chronic musculoskeletal pain patients and 20 healthy controls were divided into lean and overweight subgroups according to their BMI. Current level of chronic pain (visual analogue scale) and pressure pain thresholds (PPTs) in 16 predefined sites, classically described and tested as painful points on the lower body, were measured. Levels of reproductive hormone and lipid profiles were assessed by ELISA. Sperm concentration and motility parameters were analyzed using a computer-aided sperm analysis system. Sperm concentration, progressive motility, and percentage of hyperactivated sperm were generally lower in the chronic pain patients in both lean and overweight groups. The overweight control and the lean chronic pain groups demonstrated a significantly lower percentage of progressively motile sperm compared with the lean control group, suggesting that musculoskeletal chronic pain may have a negative influence on sperm quality in lean patients. However, due to the potential great negative influence of obesity on the sperm parameters, it is difficult to propose if musculoskeletal chronic pain also influenced sperm quality in overweight patients. Further research in chronic pain patients is required to test this hypothesis.

Male infertility: lifestyle factors and holistic, complementary, and alternative therapies

While we may be comfortable with an allopathic approach to male infertility, we are also responsible for knowledge about lifestyle modifications and holistic, complementary, and alternative therapies that are used by many of our patients. This paper provides an evidence-based review separating fact from fiction for several of these therapies. There is sufficient literature to support weight reduction by diet and exercise, smoking cessation, and alcohol moderation. Supplements that have demonstrated positive effects on male fertility on small randomized controlled trial (RCT) include aescin, coenzyme Q 10 , glutathione, Korean red ginseng, L-carnitine, nigella sativa, omega-3, selenium, a combination of zinc and folate, and the Menevit antioxidant. There is no support for the use of Vitamin C, Vitamin E, or saffron. The data for Chinese herbal medications, acupuncture, mind-body practice, scrotal cooling, and faith-based healing are sparse or inconclusive.

The impact of body mass index on semen parameters in infertile men

This hospital-based, prospective study was conducted to evaluate the relationship between body mass index (BMI) and various semen parameters in infertile men. A total of 439 men presented for infertility evaluation were assessed by basic infertility evaluation measures including semen analysis and BMI calculation. The main outcome measure was the relationship between BMI groups [BMI: 18.5-24.9 kg/m² (normal weight), 25-29.9 kg/m² (overweight) and ≥30 kg/m² (obese)] and different semen parameters [volume, concentration, motility and morphology]. The mean BMI was 29.67 ± 5.89. Most of patients (82.91%) were overweight or obese. The 3 BMI groups were comparable in semen parameters (P > 0.05). BMI had a negative correlation with various semen parameters. However, this correlation was significant only with sperm concentration (P = 0.035). We concluded that sperm concentration was the only semen parameter which showed significant reduction with higher BMI in infertile men.

Obesity and reproduction: a committee opinion

The purpose of this ASRM Practice Committee report is to provide clinicians with principles and strategies for the evaluation and treatment of couples with infertility associated with obesity. This revised document replaces the Practice Committee document titled, "Obesity and reproduction: an educational bulletin," last published in 2008 (Fertil Steril 2008;90:S21-9).

Nonalcoholic fatty liver disease and alteration in semen quality and reproductive hormones

OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the world. Some reports have shown that NAFLD may cause multisystem damage, but its influence on male reproductive function has rarely been studied.

AIM

To evaluate the influence of NAFLD on sperm quality and reproductive hormones in Chinese men.

MATERIALS AND METHODS

A total of 102 NAFLD men and 94 healthy men without fatty liver (control) were enrolled in this study. All participants underwent a physical examination, and were subjected to lifestyle questionnaires and abdominal ultrasound examination. The semen quality (volume, concentration, motility, and morphology) and serum hormonal levels (testosterone, estradiol, follicle-stimulating hormone, inhibin B, sex hormone-binding globulin, and luteinizing hormone) were examined and compared between the two groups.

RESULTS

The levels of serum testosterone and sex hormone-binding globulin were significantly lower in the NAFLD patients compared with the control group. Sperm concentration (P=0.04), sperm count (P=0.01), and total motility (P=0.03) in the NAFLD patients were significantly decreased compared with the control group. However, no significant differences were observed in semen volume and morphology. Multivariate analysis showed that sperm concentration, sperm count, and motility were significantly associated with NAFLD and abstinence (P<0.05 or P<0.001).

CONCLUSION

These results suggest that NAFLD could significantly affect sperm quality and reproductive hormones.

Paternal obesity negatively affects male fertility and assisted reproduction outcomes: a systematic review and meta-analysis

This systematic review investigated the effect of paternal obesity on reproductive potential. Databases searched were Pubmed, Ovid, Web of Science, Scopus, Cinahl and Embase. Papers were critically appraised by two reviewers, and data were extracted using a standardized tool. Outcomes were: likelihood of infertility, embryo development, clinical pregnancy, live birth, pregnancy viability, infant development, sperm; concentration, morphology, motility, volume, DNA fragmentation, chromatin condensation, mitochondrial membrane potential (MMP), and seminal plasma factors. Thirty papers were included, with a total participant number of 115,158. Obese men were more likely to experience infertility (OR = 1.66, 95% CI 1.53-1.79), their rate of live birth per cycle of assisted reproduction technology (ART) was reduced (OR = 0.65, 95% CI 0.44-0.97) and they had a 10% absolute risk increase of pregnancy non-viability. Additionally, obese men had an increased percentage of sperm with low MMP, DNA fragmentation, and abnormal morphology. Clinically significant differences were not found for conventional semen parameters. From these findings it can be concluded that male obesity is associated with reduced reproductive potential. Furthermore, it may be informative to incorporate DNA fragmentation analysis and MMP assessment into semen testing, especially for obese men whose results suggest they should have normal fertility.

High body mass index has a deleterious effect on semen parameters except morphology: results from a large cohort study

OBJECTIVE

To evaluate the influence of body mass index (BMI) on semen characteristics.

DESIGN

Cohort study.

SETTING

Single private andrology laboratory.

PATIENT(S)

All patients (n=10,665) consulting for a semen analysis from October 9, 2010, to October 8, 2011. When analyses were repeated on the same patient, only the first was included.

INTERVENTION(S)

Recording of self-reported weight and height and of semen analysis.

MAIN OUTCOME MEASURE(S)

All parameters of standard semen analysis: pH, volume, sperm concentration per mL, total sperm count per ejaculate, motility (%) within 1 hour after ejaculation (overall and progressive), viability (%), and normal sperm morphology (%). Parametric and nonparametric statistical methods were applied, and results are given either with mean±SD, or 10th, 50th, and 90th percentiles.

RESULT(S)

Semen volume decreased from 3.3±1.6 to 2.7±1.6 mL when BMI increased from normal (20-25 kg/m2) to extreme obesity (>40 kg/m2). The same was true for semen concentration (56.4±54.9 to 39.4±51.0 million/mL), total sperm count (171±170 to 92±95 million), and progressive motility (36.9±16.8% to 34.7±17.1%). The percentage of cases with azoospermia and cryptozoospermia increased from 1.9% to 9.1% and from 4.7% to 15.2%, respectively. The other semen characteristics were not affected. Multivariate models including age and abstinence duration confirmed these results.

CONCLUSION(S)

In this study, on a large patient sample size, increased BMI was associated with decreased semen quality, affecting volume, concentration, and motility. The percentage of normal forms was not decreased.