Association between body mass index and sperm quality and sperm DNA integrity. A large population study

This study aimed to analyse whether the functional quality of spermatozoa is associated with body mass index (BMI). Semen samples were obtained from 1824 men undergoing fertility evaluation/treatment. Semen analysis was performed using World Health Organization (WHO) criteria, and morphology was evaluated with the motile sperm organelle morphology examination (MSOME). The percentages of sperm DNA fragmentation (using TdT (terminal deoxynucleotidyl transferase)-mediated dUTP nick-end labelling (TUNEL) assays), sperm chromatin packaging/underprotamination (using chromomycin A3/CMA(3)), mitochondrial damage (using MitoTracker Green) and apoptosis (using annexin V) were also assessed. At least 200 spermatozoa were examined in each evaluation. The following BMI values were used as cut-off points: 24.9kg/m(2), 25-29.9kg/m(2) (overweight) and 30kg/m(2) (obese). High BMI negatively affects sperm concentration, vitality, motility and morphology (p<.05). Conversely, high BMI does not seem to be associated with impaired sperm DNA integrity, as assessed by DNA fragmentation, sperm protamination and sperm apoptosis (p>.05). However, increased BMI is associated with increased mitochondrial damage in spermatozoa (p<.05). In conclusion, given the adverse consequences of obesity and the possible effect of male BMI on assisted reproduction technology (ART) outcomes, the benefits of weight reduction should be discussed when counselling couples interested in fertility treatment.