|Ahead of print publication
Correlation of body mass index with semen parameters and testicular volume in men with infertility
Sadiq Abu1, Terkaa Atim2, Hadijat O Kolade-Yunusa3, Kenenna O Obiatuegwu4, Felix E Magnus2, Nuhu K Dakum5
1 Department of Surgery, Zenith Medical and Kidney Centre, Abuja; Department of Surgery, University of Abuja Teaching Hospital, Gwagwalada, FCT, Nigeria
2 Department of Surgery, University of Abuja Teaching Hospital; College of Health Sciences,Faculty of Clinical Sciences, University of Abuja, Gwagwalada, FCT, Nigeria
3 College of Health Sciences, Faculty of Clinical Sciences, University of Abuja; Department of Radiology, University of Abuja Teaching Hospital, Gwagwalada, FCT, Nigeria
4 Federal Medical Centre, Jabi, Abuja, Nigeria
5 Department of Surgery, Jos University Teaching Hospital, Jos, Plateau State, Nigeria
|Date of Submission||25-Sep-2020|
|Date of Acceptance||21-Apr-2021|
|Date of Web Publication||13-Aug-2021|
Department of Surgery, Zenith Medical and Kidney Centre, Abuja, FCT, Department of Surgery, University of Abuja Teaching Hospital, Gwagwalada, FCT
Source of Support: None, Conflict of Interest: None
Background: The question of whether body mass index (BMI) affects semen quality and male fertility is controversial and available evidence are inconclusive and poorly documented in Nigeria and Africa by extension. Aim and Objectives: The study was conducted to correlate body mass index, sperm parameters and testicular volume in men with infertility presenting to the urology division, University of Abuja Teaching Hospital, Gwagwalada Abuja. Material and Methods: This was a prospective cross- sectional study. Male patients with infertility who presented to Urology Division University of Abuja Teaching hospital were recruited into the study. The weight of the subjects were measured using digital scale in kilogram and the height of the subjects were measured in meters and BMI calculated. The testicular volumes of all the subjects were measured using Prader orchidometer. The semen samples were collected by the process of masturbation on day five of sexual abstinence and analyzed according to WHO 2010 criteria. Collected data were analyzed using SPSS version 20. Results: The mean BMI of the subjects was 25.97±4.57kg/m2 with a range of 18.80-44kg/m2. The mean testicular volume using the orchidometer was 12.02±3.55ml. Subjects with normal BMI were 39(45.9%), overweight 32(37.6%) and 14(16.5%) of the subjects were obese. There was strong significant negative correlation between BMI and semen concentration using Pearson correlation (r=-0.591, P=0.000), and sperm motility (r=-0.569, P=0.000). Conclusion: Although it is difficult to generalize our results to the overall population, our results suggest that increased BMI has a deleterious effect on semen concentration and sperm motility. Therefore, to ensure maximum fertility potential, patients may be advised to prevent excessive weight gain as well as reduce weight amongst the obese.
Keywords: Body mass index, Infertility, orchidometer, seminal fluid parameters, seminiferous tubules
|How to cite this URL:|
Abu S, Atim T, Kolade-Yunusa HO, Obiatuegwu KO, Magnus FE, Dakum NK. Correlation of body mass index with semen parameters and testicular volume in men with infertility. Afr J Infertil Assist Concept [Epub ahead of print] [cited 2021 Nov 28]. Available from: https://www.afrijiac.org/preprintarticle.asp?id=323872
| Introduction|| |
Infertility is a global and a public health concern in many parts of sub-Saharan Africa., Available evidence suggests that male infertility is an important but neglected reproductive health issue in Nigeria.
Infertility is defined by the World Health Organization (WHO) as the inability of a couple to achieve conception after 12 months or more of regular, unprotected sexual intercourse.
Male infertility has multi-factorial etiologies ranging from modifiable to genetic risk factors. Among all the risk factors that may account for male infertility, obesity is one of the emerging public health problems.
In the developing world, a rapidly increasing prevalence of obesity has been reported particularly in people from lower socioeconomic status., Reported prevalence of obesity in Nigeria is in the range of 20.7% and 22%.,
Little information exists on the impact of body mass index (BMI) on male fertility or semen parameters despite the fact that obesity and male factor infertility have been increasing globally over the last few decades. Seminal fluid analysis is often used in assessing male infertility based on WHO guidelines. Men who are underweight have been reported to have lower sperm concentrations when compared to men with normal BMI. However, some studies have found no relationship between BMI and semen parameters in men with infertility.
The seminiferous tubules comprise 80%–90% of the testicular mass, thus, testicular volume correlates with testicular function. Testicular volume is one of the important indices that depict the reproductive capability of a man. There is the need to correlate BMI, testicular volume, and semen parameters.
This study was, therefore, designed to determine the possible relationship between BMI, semen parameters and testicular volume in men with infertility with a view to improving our understanding of the etiology of poor semen quality as well as provide rational approaches to preventing and treating infertility in men.
| Materials and Methods|| |
The study was carried out in the urology division. This was a prospective cross-sectional study over a period of 1 year, during which time male patients seen in the Urology Clinic of the Hospital with infertility were recruited for this study. Males with infertility who consented and in whom semen could be collected were recruited into the study. Patients with azoospermia, chronic illness, testicular/scrotal pathologies, patients with Grade 2 and Grade 3 varicocele, and those on hormone or medication for chronic diseases and psychoactive drugs for more than 6 months were excluded from the study. Also, those hospitalized with serious illness or had surgery in the last 6 months were excluded from the study.
A detailed physical examination was carried out including a genital examination. The presence of a varicocele was determined by palpation and observations in the standing position before and during the Valsalva maneuver. Testicular volume of each participant was measured using Prader orchidometer and the mean testicular volume calculated. Semen was collected and analyzed according to WHO 2010 guidelines.
The subjects were weighed wearing undergarments only. The body weights of the subjects were measured using a digital weighing scale in kilogram to one decimal point and the height measured in meters to one decimal point. BMI was calculated as weight in kilograms divided by squared height in meters.
Semen was collected on day five after sexual abstinence for optimum sperm parameters in a clean, dry, wide-mouthed biologically inert plastic container by the process of masturbation. Semen samples were collected in a room close to the laboratory and at home for patients who could not produce semen in the hospital with clear written and oral instructions on collection and transportation, with emphasis on complete sample, that is, all the ejaculate was collected including the first sperm-rich portion and loss of any of the sample was reported. The collected samples were allowed to liquefy at 37°C for 30 min and analyzed within 1 h of collection. Microscopic examination was carried out to record the total sperm count, motility, and morphology of the sperm according to WHO Guideline (2010) in the microbiology research laboratory. Two semen samples were collected on two different occasions 2 weeks apart, from each subject for analysis due to individual variability in semen parameters and the sample with better semen parameters was used for this study.
Informed consent was obtained from each participant before including him in this study and ethical approval for the study was obtained.
Collated data were analyzed using SPSS version 20.0 (IBM SPSS Statistics for Windows, Version 20.0. Armonk, New York: IBM Corp) and P < 0.05 was considered to be statistically significant. Test of significance was done using independent t-test. Pearson correlation coefficient worked out to assess the linear relationship of testicular volume and BMI with different sperm parameters.
| Results|| |
A total of 85 men with infertility were recruited for this study over a period of 1 year. The mean age of men with infertility in this study was 39.22 ± 6.27 years with the age range of 28–54 years. The mean BMI of the subjects was 25.97 ± 4.57 kg/m2 with a range of 18.80–44 kg/m2. A large proportion of the men were civil servants, 48 (56.6%). About two-thirds of the men attained a tertiary level of education 51 (60%). The average right testicular volume of men with infertility was 12.02 ± 3.76 ml which was slightly more than the average left testicular volume of 11.24 ± 3.83 ml. Though the difference is not statistically significant (t = 1.5, P = 0.805). The mean testicular volume in this study was 12.02 ± 3.55 ml with a range of 5.0–24 ml. A high proportion of the subjects had normal BMI 39 (45.9%) and 14 (16.5%) of the subjects were obese. Among the obese subjects, 10 (71.4%) had class1 obesity, 3 (21.4%) had class II obesity and 1 (7.2%) had class III obesity [Table 1].
|Table 1: Sociodemographic and clinical characteristics of the patients (n=85)|
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[Table 2] shows there is weak correlation between mean testicular volume (MTV) and height but not statistically significant (r = 0.094, P = 0.393). The weak relationship between MTV and weight of subjects was not statistically significant (r = 0.182, P = 0.096).
|Table 2: The relationship between mean testicular volume of men with infertility and height (m) and weight (kg)|
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There was an inverse relationship between BMI of men with infertility and sperm concentration. The mean sperm concentration of men with infertility was highest among subjects with normal BMI (10.2 ± 3.4 million/ml) and least for the obese men with infertility (2.1 ± 1.0 million/ml). There was a strong significant negative correlation between BMI and semen concentration using Pearson correlation (r = −0.591, P = 0.000). There was an inverse relationship between BMI and mean sperm motility of men with infertility. Subjects with normal BMI having the highest sperm motility (50.5 ± 17.2%) and the obese subjects having the least sperm motility (8.2 ± 5.6%). There is a significant negative correlation between BMI and sperm motility using Pearson correlation (r = −0.569, P = 0.000). Overweight subjects had the highest sperm morphology (64.4%) and obese subjects had the lowest (53.6%). There was a weak negative correlation between BMI of men with infertility and sperm morphology and it was not statistically significant (r = −0.187, P = 0.086). Overweight subjects had the highest testicular volume measured by Orchidometer (13.9 ml) while normal-weight subjects had a mean testicular volume of 10.4 ml. There was a weak positive correlation between BMI and MTV in this study but not statistically significant (r = 0.263, P = 0.015) [Table 3].
|Table 3: The relationship between body mass index and sperm parameters with mean orchidometric testicular volume|
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[Table 4] shows there was a corresponding decrease in semen concentration and MTV with increasing level of obesity. However, class II obese subjects show no sperm motility and also show lower normal sperm forms (6.7%) than the class III obese individuals (20.0%).
|Table 4: The relationship between various classes of obesity, semen parameters, and mean testicular volume (n=14)|
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| Discussion|| |
Studies have suggested that the incidence of overweight and obesity in men of reproductive ages is rising and this may affect fertility.
In this study, the mean age was 39.22 years with age range of 28–54 years. This is similar to the findings of 38.7 years by Abuhulimen et al. in a multicenter study in Nigeria on the impact of obesity on male fertility. This also falls into the reproductive age group which are the ones who come to the urologic outpatient clinics for fertility consultation. About two-thirds of the subjects attained tertiary level of education, 60%, which is similar to the findings by Obese et al. among men with infertility in Benin-City where 65.5% of the subjects attained tertiary level of education. Abuhulimen et al. also reported that 64.3% of subjects had tertiary education in a similar study among male partners of infertile couples.
The proportion of men with infertility with normal BMI was 39 (45.9%) while obese was 14 (16.5%). This is in tandem with a recent work by Obese et al. on relationship between obesity and semen quality in men with infertility in Benin-City, Nigeria where about half (53.4%) of the subjects had normal BMI, 25.2% overweight and 21.4% were obese, respectively. This finding is however different from a similar study by Alshahrani et al. among men with infertility in Saudi Arabia where most of the subjects were overweight or obese (82.91%). Similarly, a cross-sectional study among males with infertility by McDonald and colleagues in New Zeeland found a mean BMI of 27.1 kg/m2, with 72.8% overweight or obese. This may be a result of racial differences in BMI.
The mean BMI of the subjects with class I obesity was 31.5 kg/m2 which accounted for 10 (71.4%) of the obese subjects in the study population. Class II obese subjects with BMI of 36.2 kg/m2 were 3 (21.4%) while 1 (7.2%) had a class III BMI of 44.7 kg/m2. These findings are comparable to the findings of a similar multicenter study in Nigeria by Abuhulimen et al. with a similar sample size of 85 who found class I obesity to be highest among men with infertility of 33 (78.6%) with a mean BMI of 31.7 kg/m2, class II obesity with mean BMI of 36.5 kg/m2 to be 7 (16.6%) and class III obesity with mean BMI of 41.6 kg/m2 to be 2 (2.8%), respectively. The slightly higher values in this study can be explained because they studied the impact of obesity on semen parameters with the lowest BMI of subjects being 30 kg/m2.
There is an inverse relationship between BMI of men with infertility and sperm concentration as there is a negative strong statistically significance between BMI and sperm concentration in men with infertility (r = −0.591, P < 0.001). This finding is in accordance with a study on male partners of pregnant women by WHO that noted that the incidence of low sperm concentration was higher in overweight and obese men than in normal-weight men. Similarly, a recent study by Najafi et al. showed a relatively decrease in sperm count among overweight and obese men when compared with men with normal BMI.
In a cross-sectional study of 1558 Military conscripts undergoing physical examination in which men with normal BMI were compared with BMI >25 kg, the total sperm count per ejaculate was reduced by 24% in men with a BMI >25 kg/m2., Chavarro et al. found a negative correlation between BMI and sperm concentration and McDonald et al. showed that the inverse relationship was reported only in sub-fertile men but not the fertile men. Data from LIFE study by Eisenberg et al. that evaluated the relationship between BMI, waist circumference and semen quality found that overweight and obesity are associated with a higher prevalence of low total sperm count. Hammische et al. reported that sperm concentration and total motile sperm count in men of subfertile couples are detrimentally affected by a high BMI and central adiposity., These findings could suggest that normal spermatogenesis requires an ideal BMI.
There is a strong significant negative correlation between BMI and sperm motility (r = −0.569, P < 0.001). This finding is similar to the report of Jensen et al. which showed a significant reduction of normal motile sperms with increasing BMI. Najafi et al. also reported a decrease in sperm motility among overweight and obese men. However, Martini et al. in a South American study of 794 men attending reproductive clinic reported BMI had a significant negative correlation with sperm motility, but no relationship with sperm concentration.
The 2010 WHO criteria state that a sample is normal if 4% (or 5th centile) or more of the observed sperm have normal morphology. Evaluation of morphology is still debatable and can be affected by the bias of the observer and lack of objective assessment. Unsurprisingly, this is the area of diagnostic semen analysis where studies have found conflicting effects on BMI. We report a weak negative correlation between BMI of men with infertility and sperm morphology and it was not statistically significant. This is comparable to findings of a military study of 1558 conscripts that found out that abnormal BMI adversely affects sperm morphology, although this effect was not statistically significant. On the contrary, studies by Pauli et al. showed no association between abnormal BMI and sperm morphology.
The mean testicular volume of subjects in this study was 12.02 ml with a range of 5–24 ml. The mean testicular volume obtained by Aribarg among fertile Thai men using orchidometer was 17.2 ml with a similar range of 6–25 ml and found that testicular volume was related to height, weight, and the ponderal index. Though the range of testicular volumes obtained is similar, the Thai men had a higher mean testicular volume. This is comparable to the orchidometric mean testicular volume (15 ml) reported for normal subjects and racial factor.
There is a weak positive correlation between BMI and MTV in this study (r = 0.263, P = 0.015). This result is comparable to the findings in a community study of 1792 healthy men in Seoul, Korea by Ku et al. who found that there were significant but weak correlations between testicular volumes and height, body weight, and BMI after excluding pathologies that can affect testicular volume. Sobowale and Akiwumi in Ilorin, Nigeria found a positive linear correlation between total testicular volume, height, weight, and ponderal index of men with infertility (r = 0.96, P < 0.001).
| Conclusion|| |
The results of this study show that the mean BMI of men with infertility was 25.97 kg/m2. BMI has a significant negative correlation with sperm concentration and sperm motility. There is a weak and insignificant correlation of BMI with normal sperm morphology and mean testicular volume in men with infertility. These findings show that increased BMI has a deleterious effect on semen concentration and sperm motility. Thus, to ensure maximum fertility potential, patients may be advised to prevent excessive weight gain as well as reduce weight among the obese men with infertility.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]