Abstract
Overweight and obese men have been reported to have lower sperm quality. The aim of this study was to evaluate, whether body mass index (BMI) is related to changes in semen parameters. In a cross-sectional study, sperm parameters were reviewed in 852 normal, healthy men, of reproductive age (25–50). BMI was divided into four groups: underweight, normal, overweight and obese. Sperm concentration of overweigh and obese men were 63 and 62, respectively, which were lower than subjects with normal BMI (71). Total sperm count and sperm motility in overweight and obese men were significantly lower than men with normal BMI too. Sperm morphology in study groups was similar. The results revealed a significant inverse correlation between the BMI and the sperm parameters.
Keywords:
Introduction
Obesity is a well recognised risk factor for female infertility [Citation1]. Overweight and obese female typically are insulin resistant [Citation2], have polycystic ovarian syndrome [Citation3] and have a poor fertility prognosis [Citation4]. It is well documented that excessive weight can also lead to spontaneous abortions [Citation5,Citation6]. However, its relation to decreased sperm count was not documented until recently [Citation7,Citation8]. It is known that the incidence of obesity is reaching epidemic levels in the western world (including male infertility). Recently, the prevalence of male obesity in the US was reported to be 30.6% [Citation9].
Male factors alone constitute 25–30% of all cases of infertility, and they contribute to another 30% in combination with female factors. Known aetiologies of male infertility include cryptorchidism, testicular torsion or trauma, varicocele, seminal tract infections, anti-sperm antibodies, hypogonadotropic hypogonadism, gonadal dysgenesis and obstruction of the reproductive channels [Citation10]. Obesity was recently proposed for addition to this list [Citation7]. Thus, obesity is a chronic disease resulting in compromised physical and psychological well-being, and it may contribute to reduced fecundity as well [Citation11].
Little information exists on the impact of body mass index (BMI) on male fertility or semen parameters. It is possible that the increasing prevalence of overweight and obesity accounts for a portion of the trend, albeit a widely debated one, of decreasing sperm counts over recent decades. Some epidemiological studies have investigated that, high or low BMI was associated with reduced semen quality [Citation7,Citation12,Citation13]. Some studies show that men with excess body weight are at increased risk of infertility [Citation7,Citation14,Citation15]. Despite the published literature on male semen quality and reproductive hormones and BMI [Citation14,Citation16], only one study could be found in the literature that had examined the relationship between individual BMI and semen parameters in fertile men with normal reproductive endocrines status such as luteinising hormone (LH), follicle stimulating hormone (FSH), testosterone (T) and estradiol (E2) [Citation18]. Our study objective was to determine the relationship between BMI and semen parameters (sperm quantity) in fertile men with normal reproductive endocrines status (without intermediate role of reproductive hormones).
Methods
Eight hundred fifty two normal, healthy men, of reproductive age (ranges 25–50 years) were enrolled in a cross-sectional study from October 2004 to September 2006 in Shahid Sedughi hospital, Yazd, Iran. The subjects were selected in both urban areas and rural areas. Men who suffered from chronic diseases such as diabetes, kidney disease, atherosclerosis, vascular disease and hypertension were excluded from the study. Subjects with genital diseases, heavy smoking were also excluded. None of the men had previous surgery (e.g., vasectomy reversal or varicocele removal). The trained staff informed the subjects about the study and obtained their informed consent.
All subjects completed a questionnaire on the day of the physical examination by face-to-face interview. The questionnaire included information on their demographic characters. Physical examinations were performed by a trained physician (urologic trained physicians). Blood samples were collected from a cubital vein. Serum concentrations of hormones (T, FSH, LH and E2) were measured by radioimmunoassay, and abnormal results excluded from study.
The weight of the subjects was measured in kilograms using one weighing scale (Seca 880 Weight Scale); Height was measured in centimeters without shoes (Leicester Height Measure). The BMI was calculated as weight in kilograms divided by the squared height in meters (kg/m2). The possible presence of a varicocele, a hydrocele, the location of testis in scrotum, and the consistency of the testis and epididymis were also recorded. Patients were grouped according to published BMI ranges as follows: underweight, <18.5 kg/m2; normal, 18.5–24.9 kg/m2; overweight, 25–30 kg/m2 and obese, >30 kg/m2 [Citation19].
Semen specimens were collected in the morning, by masturbation in a sterile plastic container in a private room near the laboratory after a period of 2 days of sexual abstinence. A single semen sample was collected from each man. All the semen samples were kept at 37°C to liquefy (After 30-min liquefaction) to make routine semen analysis according to the World Health Organization guidelines [Citation20]. The semen smears were air-dried, stained and preserved, and the same technician assessed blindly all the smeared slides to determine sperm morphology. Smears were examined under oil immersion, the semen characteristics were quantified by using a Makler semen counting chamber under the 200× magnification of an Olympus CH 2 phase contrast light. The following semen variables were used as outcome variables: semen volume, sperm concentration, total sperm count, percentage of motile spermatozoa (percentage of sperm with rapid and linear progressive motility and sluggish linear motility). Normal values for standard sperm parameters were considered as sperm concentration ≥20 × 106/ml, total sperm count ≥40 × 106/ejaculate and percentage of sperm motile ≥50% [Citation20]. Data from all patients were used in the analysis. SPSS 15.0 was used for statistical analysis. The t-test was used to compare differences between the two groups, and P value <0.05 considered statistically significant.
Results
Characteristics of subjects were shown in . The subjects had the BMI of 24.7 ± 3.6 kg/m2. 16 subjects (1.8%) were classified as underweight, 604 (70.9%) as normal weight, 213 (25%) as overweight and 19 (2.2%) as obese. Most of the study population (91.4) has ≥12 years of education. There were no significant differences between BMI groups for abstinence and smoking. No seasonal changes in this study population were observed in terms of semen quality.
Table I. Characteristics of study population according to different body mass index (BMI) groups.
The results revealed a significant correlation between the BMI and the sperm concentration, total sperm count and motile sperm. Median sperm concentration of overweight and obese men were 63 and 62, respectively (P = 0.02 and P = 0.01, respectively) which were lower than the subject with normal BMI. Total sperm count in overweight and obese men were significantly lower than normal men too (100 and 94, respectively P = 0.00 in both). There were no significant difference in concentration and total sperm count between underweight men and normal group. Sperm motility in the obese men was lower than normal group, (50 vs. 68, P = 0.00) but in overweight and underweight, had no significant differences. Sperm morphology in study groups was similar .
Table II. Estimated mean ± SD of semen analysis between different body mass index (BMI) groups.
Discussion
Body mass index is associated with alterations in sperm parameters in several reports. However, its relation to decreased sperm count was not documented until recently [Citation7,Citation21]. In a recent study investigating factors associated with semen quality among couples who visited an assisted reproduction clinic, men with poor semen quality were three times more likely to be obese than men with normal semen quality. There was also a significant negative correlation between semen quality parameters and BMI among men with normal semen quality [Citation8]. In this study, an inverse relationship between overweight and obesity and the total number, concentration and number of motile sperm cells per subject was observed. Men with a BMI >25 kg/m2 have fewer sperm number, concentration and number of normal motile sperm cells per ejaculate when the BMI was >30 kg/m2. Our results confirm the findings of many other studies [Citation7,Citation8,Citation11], which have shown that sperm quality especially sperm concentration and normal motile sperm cells, decrease as body weight increases. However, our study is unique in that, it clearly shows the effects of BMI on sperm quality and this information is obtained from overweight men who have normal reproductive hormones and it is different from other studies, that included reproductive hormones to explain the association between BMI and semen quality [Citation14]; or examine the relationship of semen parameters, sexual function-related hormones and waist/hip ratio [Citation12]; or the study that showed overweight and obese men have a markedly changed sex hormone profile in serum, whereas reduction of semen quality [Citation22].
In converse to Qin et al. [Citation14] study, in this study there were no significant differences in total number, concentration and number of motile sperm between underweight and normal men. An interesting finding from the regression analyses is that overweight men have the same number of motile sperm as normal men. Therefore, there is a rapid loss of sperm motility with modest weight gain.
Conclusion
In conclusion, the current study indicated that semen parameter was reduced among overweight and obese men compared with normal BMI and this can be important in infertile couple with male factor and their treatment programme, and weight loss can improve semen quality.
Acknowledgement
The authors are thankful to the laboratory personnel of Shahid Sedughi hospital.
Related Research Data
References
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