High body mass index has a deleterious effect on semen parameters except morphology: results from a large cohort study.

Objective To evaluate the influence of body mass index (BMI) on semen characteristics. Design Cohort study. Setting Single private andrology laboratory. Patient(s) All patients (n = 10,665) consulting for a semen analysis from October 9, 2010, to October 8, 2011. When analyses were repeated on the same patient, only the first was included. Intervention(s) Recording of self-reported weight and height and of semen analysis. Main Outcome Measure(s) All parameters of standard semen analysis: pH, volume, sperm concentration per mL, total sperm count per ejaculate, motility (%) within 1 hour after ejaculation (overall and progressive), viability (%), and normal sperm morphology (%). Parametric and nonparametric statistical methods were applied, and results are given either with mean ± SD, or 10th, 50th, and 90th percentiles. Result(s) Semen volume decreased from 3.3 ± 1.6 to 2.7 ± 1.6 mL when BMI increased from normal (20–25 kg/m 2 ) to extreme obesity (>40 kg/m 2 ). The same was true for semen concentration (56.4 ± 54.9 to 39.4 ± 51.0 million/mL), total sperm count (171 ± 170 to 92 ± 95 million), and progressive motility (36.9 ± 16.8% to 34.7 ± 17.1%). The percentage of cases with azoospermia and cryptozoospermia increased from 1.9% to 9.1% and from 4.7% to 15.2%, respectively. The other semen characteristics were not affected. Multivariate models including age and abstinence duration confirmed these results. Conclusion(s) In this study, on a large patient sample size, increased BMI was associated with decreased semen quality, affecting volume, concentration, and motility. The percentage of normal forms was not decreased. [ABSTRACT FROM AUTHOR]