Open Journal of Obstetrics and Gynecology
Vol.04 No.15(2014), Article ID:51190,6 pages
10.4236/ojog.2014.415129
Obesity Appears to Impact Male Fertility by Degrading Overall Semen Quality Rather than Individual Semen Parameters
Joseph Petty1, Sami Jabara1, Samuel Prien1,2, Lindsay Penrose1
1Department of Animal and Food Sciences, Texas Tech University, Lubbock, USA
2Department of Obstetrics and Gynecology, Texas Tech University Health Sciences Center, Lubbock, USA
Email: samuel.prien@ttuhsc.edu
Copyright © 2014 by authors and Scientific Research Publishing Inc.
This work is licensed under the Creative Commons Attribution International License (CC BY).
Received 22 August 2014; revised 20 September 2014; accepted 15 October 2014
ABSTRACT
Obesity has become a well-recognized medical issue. However its exact role in male infertility remains unclear. The objective of the current study was to determine if an increase in
Keywords:
Body Mass Index, Obesity, Semen Analysis, Sperm Morphology
1. Introduction
Obesity is a growing health concern. The Behavioral Risk Factor Surveillance System, in conjunction with the CDC, conducted a national survey in 2000 and found that, the prevalence of obesity (
A number of previous studies have described a correlation between obesity and male factor infertility. However, they appear to offer no definitive cause for the relationship. A Danish study by Jensen et al. enrolled 1558 young men (mean 19 years old) when they presented for their compulsory physical exam as part of their country’s military drafting system [5] . The authors demonstrated decreased sperm counts and concentration (39 million/mL vs. 46 million/mL) in those with an elevated
Other studies have attempted to find alternate explanations for how obesity can be detrimental to male fertility by focusing on sexual function. Sallmén et al. conducted a survey-based population study focused on couples that had attempted pregnancy in the prior four years. They found a dose-dependent effect of increasing
From these previous studies there appears to be general agreement that male obesity can affect fertility, yet there appears to be a lack of consensus as to the mechanisms involved. Further, while a number of studies have examined the relationship between
2. Materials and Methods
In the present study, charts were reviewed for all male patients who presented for an infertility consultation and evaluation at the Texas Tech Physicians Center for Fertility and Reproductive Surgery during an 18 month period in 2008-2010. To be included in the study the male partners had to have presented for a face-to-face interview to review their history and record their vital statistics (i.e. height and weight) as part of the couple’s infertility workup. Patients were excluded if their questionnaire was missing or if they had an otherwise incomplete chart. By default, this excluded any patient who had missing vital statistics (i.e. height and weight), which would have prevented the calculation of their
The patient intake questionnaire included questions regarding their demographic, medical, surgical and fertility history, as well as a series of questions which allowed the analysis of confounding variables known to be associated with fertility or infertility issues. These included: proven fertility, psychiatric disorders, tobacco use, alcohol use, chemical exposure, genitourinary anomalies, and other medical conditions. Proven fertility for the male partner was defined as pregnancies fathered with either the current or previous partners. Psychiatric disorders included any degree of depression, bipolar disorder or any other psychiatric disorder requiring medical therapy. Further patients were considered to be tobacco and/or alcohol users whether they admitted to light, moderate, or heavy use. Chemical exposures included contact with pesticides, herbicides, and heavy metals, were all considered especially pertinent given the prominent agriculture industry in the study environment. Sexual dysfunction included mainly erectile dysfunction and decreased libido. Genitourinary anomalies included hypospadias and varicocele. Patients were also asked about surgery to correct genitourinary anomalies or for other reasons such as testicular torsion or inguinal hernia or trauma. Other medical problems reviewed included mainly diabetes, hypertension, thyroid disease, autoimmune disease, and cancer.
The
Resulting data were analyzed by analysis of variance (ANOVA) and post-hoc Tukey HSD tests between the groups using the Statistical Package for the Social Sciences software (SPSS ver. 12; Chicago, IL). A P-value < 0.05 was considered statistically significant. In addition to analyzing the effects of BMI on single semen parameters, semen parameters for each patient were combined into NMS after the technique of Kort et al. [6] .
3. Results
The demographic characteristics and confounding variables appeared similar in all three
Table 1. Demographic difference of men with normal, overweight and obese BMI seeking infertility treatment.
*PFP―previously fathered pregnancy; GUA―genitourinary anomalies; GUS―genitourinary surgeries.
psychiatric problems were 13%, 5%, 0% (P = 0.57). The subjects had reported rates of tobacco 17%, 26%, 18% (P = 0.77), and alcohol use was seen in 50%, 58%, 53% (P = 0.74) of patients, which were similar for all three groups. The self-reported rates of sexual dysfunction were 8%, 7%, and 16% between the three groups (P = 0.80). In addition, individuals from each group had similar rates of other medical problems not categorized for this study (38%, 23%, and 31%; P = 0.90). Finally, as the study was based in a region that is heavily involved in agriculture and the petroleum industry, patients were asked about toxin exposure. The resulting rates of exposure were minimal and similar between the three group (4%, 0% and 0%; P = 0.17). The data did suggest a potential difference (trend) in genitourinary anomalies (0%, 9%, and 9%; P = 0.06), and surgeries involving the genitourinary system (21%, 5%, 16%; P = 0.057), with the normal BMI group having had the fewest current anomalies but the most corrective surgery. However the p-values did not rise to the level of significance.
While there were some numerical trends in the data sets, there were no statistical differences seen in any of the individual semen parameters examined between the three
While no single semen characteristic reached significance in this study, when the technique of Kort et al. [6] was applied looking for an effect of obesity on the total normal motile sperm cells, there appears to be differences between the groups (Figure 2; P < 0.032). Men with normal BMI had significantly higher NMS than the obese group with the overweight individuals having an intermediate value between the two.
Figure 1. A comparison of sperm cell concentration (millions/mL) from men with a normal, (20 - 24 kg/m2), overweight (25 - 30 kg/m2), or obese (>30 kg/m2) BMIs. Bars with similar subscripts are not significantly different (P = 0.18).
Figure 2. The total normal motile sperm count (NMS; millions/mL) from men with a normal, (20 - 24 kg/m2), overweight (25 - 30 kg/m2), or obese (>30 kg/m2) BMIs. Bars with different subscripts are significantly different (P < 0.03).
Table 2. A comparison of four common semen parameters from men with a normal, (20 - 24 kg/m2), overweight (25 - 30 kg/m2), or obese (>30 kg/m2) BMIs.
*Morph-semen morphology; Vol-volume; Agg-agglutination. All normal values were determined using the WHO guide version 3 which was in use at the time of this study [11] .
4. Discussion
In the present study, there appeared to be no direct association between
If these previously described deceases in concentration are real, they might be explained by the fact that obesity can change the normal hormonal milieu, leading to decreased spermatogenesis. This could explain the Danish study by Jensen et al. [5] , which while from a much larger population, was limited to individuals of relatively young age. However, the common population seeking infertility treatment is typically older; as seen in the average age of the present study being between 33 - 34 years old. It is Important to note that obesity is thought of as a chronic and progressive disease process and it could take time to manifest effects on the semen profile. This might explain the lack of correlations in the Danish study dealing with only young men, one would assume in generally good physical shape as they were being inducting into military service. However, given the current trend toward obesity at younger ages [10] [15] [16] , this may become an issue of concern.
By contrast, the Kort et al. [6] study examined volume, concentration, motility and morphology in a combined score. In doing so, it is unclear which specific parameters in the semen analysis profile were more affected by obesity. The same low NMS score could be obtained using different data points, with each having vastly different findings in the semen analysis. The data from the current study also demonstrated a decrease in total number of normal motile cells with increasing BMI, suggesting it might be the combined effects of obesity on the sperm cell structure and function which leads to lower fertility and not the effect on one single parameter alone. Further, it would appear the effects of obesity on male fertility vary widely between individuals, but appears to be the result of changes in normal hormonal patterns. While a number of recent studies have attempted to elucidate these interactions, no definitive relationships have immerged [12] - [14] [17] [18] . This may be due to the complexity of the hormonal arc that leads to normal sperm cell development.
5. Conclusion
While the present study is retrospective and consists of a relatively small number of subjects, it appears to be one of the first to attempt to correct for biases seen in earlier studies by including face-to-face interviews to confirm information recorded on patient questionnaires. While the lack of a direct correlation between any single semen parameter and infertility may be due to the size limitation of the study, the decreased NMS confirms the earlier work of Kort et al. [6] , and suggests the increased
Acknowledgements
Special thanks go to Amantia Kennedy for help with data collection. Also thank you to the staff at The Center for Fertility & Reproductive Surgery and Dr. Prien’s lab at TTUHSC.
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