Association of body mass index with some fertility markers among male partners of infertile couples

The available evidence on the role of obesity and body mass index (BMI) on male infertility has been controversial or inconclusive to some extent.
Objectives: The aim of this study was to investigate the role of BMI on some male-fertility laboratory indicators both among infertile and fertile men in an Iranian population.
Methods and materials: A total of 159 male patients who had lived as a partner in an infertile couple for at least 1 year, after regular reproductive activity in their married life, and who sought infertility consultation, were investigated. BMI was assessed, and a morning blood sample was taken assessing serum levels of testosterone, sex hormone-binding globulin, prolactin, luteinizing hormone (LH), follicle-stimulating hormone, and estradiol. Semen-analysis parameters were also measured.
Results: In this study, it was found that the likelihood of oligospermia was increased at higher BMI values. Obese men were found to be 3.5 times more likely to have oligospermia than those with normal BMI. BMI was not found to be associated with mean numeric values of the semen-analysis parameters, including sperm count, sperm morphology, and sperm motility. BMI was not significantly correlated with some hormone levels, such as LH, prolactin, and LH/follicle-stimulating hormone ratio. However, a statistically significant association was observed between BMI and estradiol (P , 0.01), sex hormone-binding globulin (P , 0.001), and also the testosterone/estradiol ratio (P , 0.001). A different pattern of associations in this study was observed when the associations between BMI and sexual hormone levels were compared between fertile and subfertile/infertile men.
Conclusion: The association explored between BMI and some sexual hormones and semen characteristics, as well as different patterns of this association between fertile and subfertile/infertile men, will be of help to broaden our understanding of the effect of obesity on some male reproductive physiologic characteristics among fertile and infertile men.