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/m2) to extreme obesity (>40 kg/m2). 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.
Belloc, S., Cohen-Bacrie, M., Amar, E., Izard, V., Benkhalifa, M., Dalléac, A., & De Mouzon, J. (2014). High body mass index has a deleterious effect on semen parameters except morphology: Results from a large cohort study. Fertility and Sterility, 102(5), 1268–1273. https://doi.org/10.1016/j.fertnstert.2014.07.1212