BACKGROUND The global obesity epidemic has paralleled a decrease in semen quality. Yet, the association between obesity and sperm parameters remains controversial. The purpose of this report was to update the evidence on the association between BMI and sperm count through a systematic review with meta-analysis. METHODS A systematic review of available literature (with no language restriction) was performed to investigate the impact of BMI on sperm count. Relevant studies published until June 2012 were identified from a Pubmed and EMBASE search. We also included unpublished data (n = 717 men) obtained from the Infertility Center of Bondy, France. Abstracts of relevant articles were examined and studies that could be included in this review were retrieved. Authors of relevant studies for the meta-analysis were contacted by email and asked to provide standardized data. RESULTS A total of 21 studies were included in the meta-analysis, resulting in a sample of 13 077 men from the general population and attending fertility clinics. Data were stratified according to the total sperm count as normozoospermia, oligozoospermia and azoospermia. Standardized weighted mean differences in sperm concentration did not differ significantly across BMI categories. There was a J-shaped relationship between BMI categories and risk of oligozoospermia or azoospermia. Compared with men of normal weight, the odds ratio (95% confidence interval) for oligozoospermia or azoospermia was 1.15 (0.93-1.43) for underweight, 1.11 (1.01-1.21) for overweight, 1.28 (1.06-1.55) for obese and 2.04 (1.59-2.62) for morbidly obese men. CONCLUSIONS Overweight and obesity were associated with an increased prevalence of azoospermia or oligozoospermia. The main limitation of this report is that studied populations varied, with men recruited from both the general population and infertile couples. Whether weight normalization could improve sperm parameters should be evaluated further.

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BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis

https://europeanurology.com/article/S0302-2838(16)30069-0/pdf/cigarette-smoking-and-semen-quality-a-new-meta-analysis-examining-the-effect-of-the-2010-world-health-organization-laboratory-methods-for-the-examination-of-human-semen

Cigarette Smoking and Semen Quality: A New Meta-analysis Examining the Effect of the 2010 World Health Organization Laboratory Methods for the Examination of Human Semen

Association between socio-psycho-behavioral factors and male semen quality: systematic review and meta-analyses

Background Several studies have suggested a population-wide decline in the quality of semen over the past 50 years, but clear evidence of decreasing semen quality in recent decades is lacking. Methods From 1973 through 1992 we measured the volume of seminal fluid, the sperm concentration, and the percentages of motile and morphologically normal spermatozoa in 1351 healthy fertile men. The data on the semen samples were collected at one sperm bank in Paris. The data in each calendar year were analyzed as a function of the year of donation, the age of each patient, the year of birth, and the duration of sexual abstinence before semen collection. Results There was no change in semen volume during the study period. The mean concentration of sperm decreased by 2.1 percent per year, from 89 ×106 per milliliter in 1973 to 60×106 per milliliter in 1992 (P<0.001). During the same period the percentages of motile and normal spermatozoa decreased by 0.6 percent and 0.5 percent per year, respectively (both P<0.001). ...

Decline in Semen Quality Among Fertile Men in Paris During the Past 20 Years

Consistent age-dependent declines in human semen quality: A systematic review and meta-analysis

background: Large studies on semen quality of the general healthy population from China are rare. methods: A cross-sectional study was performed to evaluate the semen quality of 1346 healthy men residing in Chongqing area of south- west China in 2007. The semen parameters were measured and compared with the World Health Organization (WHO) criteria. A linear regression model was used to examine the determinants of semen quality. results: The medians were 2.3 ml for semen volume, 77.8 � 10 6 per ml for semen concentration, 167.7 � 10 6 for total sperm count, 33% for sperm rapid progressive motility, 52.6% for sperm progressive motility and 70.9% for total motility. According to WHO criteria, 61.1% of healthy males had at least one semen parameter below normal threshold values. Season and abstinence duration were found to be significantly associated with semen quality (P , 0.001). Age, smoking, alcohol use and BMI had little or no effect on semen parameters. conclusions: A high proportion of healthy males in Chongqing area of southwest China had abnormal semen parameters values according to WHO criteria. The semen parameters in the study population were markedly different from those reported for the other Chinese, USA and European populations. The differences remain unexplained and may be due to demographic characteristics, lifestyle, environmental factors or genetic variation.

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Semen quality of 1346 healthy men, results from the Chongqing area of southwest China

Background: Recent observations in in vitro and in vivo models suggest that arsenic (As) is an endocrine disruptor at environmentally-relevant levels. When exposed to As, male rats and mice show steroidogenic dysfunction that can lead to infertility. However, the possible effects of As on human male semen quality remain obscure.

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Chuanhai Li

Papers

Semen quality of 1346 healthy men, results from the Chongqing area of southwest China

Environmental exposure to arsenic may reduce human semen quality: associations derived from a Chinese cross-sectional study