Influence of increasing body mass index on semen and reproductive hormonal parameters in a multi-institutional cohort of subfertile men

Objective To determine whether obesity affects serum and seminal measures of male reproductive potential among a multi-institutional cohort. Design Retrospective multi-institutional cohort study. Setting Infertility clinics. Patient(s) All men referred for male infertility evaluation from 2002 to 2014 (n = 4,440). Intervention(s) None. Main Outcome Measure(s) Collected reproductive parameters included hormonal (gonadotropins, T, E₂, PRL) and semen analysis (ejaculate volume, sperm concentration, motility, normal morphology) data. Body mass index (BMI) was calculated for all patients with comparisons to reproductive parameters using univariate and multiparametric models. Result(s) Based on World Health Organization definitions, 30.9% of the cohort was normal weight (BMI 18.5–24.9), 45.1% overweight (25–29.9), and 23.3% obese (>30). Neither FSH nor LH demonstrated significant correlations with BMI on multivariate analysis. Total T (r = −0.27) and the T:E₂ ratio (r = −0.29) inversely varied with BMI, whereas E₂ (r = 0.13) had a direct correlation. On univariate analyses, BMI had weak but significant negative correlations with ejaculate volume (r = −0.04), sperm concentration (r = −0.08), motility (r = −0.07), and morphology (r = −0.04). All parameters remained significant on multivariate modeling with the exception of sperm motility. Rates of azoospermia and oligospermia were also more prevalent among obese (12.7% and 31.7%, respectively) compared with normal weight men (9.8% and 24.5%). Conclusion(s) In one of the largest cohorts of male fertility and obesity, serum hormone and semen parameters demonstrated mild but significant relationships with BMI, possibly contributing to subfertility in this population.