Lifestyle factors impact sperm microbiota and are associated with biological and clinical issues in infertile patients undergoing assisted reproductive technologies, a proof-of-concept study.

Sperm microbiota originates from local (urogenital, intestinal, cutaneous) and partner microbiomes, influenced by sexual activity. Its composition and diversity may impact male fertility, but research remains limited. This study aimed to investigate the relationship between lifestyle factors, sperm microbiota composition, and fertility outcomes. A monocentric prospective study was conducted on men undergoing assisted reproductive technology at Poitiers University Hospital between May and December 2021. Samples were analysed using high-throughput sequencing and bioinformatic pipelines to assess microbial diversity, taxonomic composition, and relative abundance. Lifestyle factors (BMI, diet, tobacco, alcohol, stress, physical activity) were collected through self-administered standardized questionnaires and medical interviews. Sperm quality was evaluated based on WHO 2021 criteria. Alpha and beta diversity metrics were calculated, and statistical correlations were assessed using ANCOM and LEfSe analyses. Two profiles were identified: one defined by Actinomycetota predominance (> 50%) (n = 34 patients) and the other by Bacillota predominance (n = 10 patients). Sperm microbiota alpha diversity was found to be higher in patients under 31 years of age or over 40 years of age, with a BMI ≥ 30, high fat intake, red meat consumption, and lower tobacco consumption (p < 0.05). Sperm microbiota beta diversity was found to differ according to age, sugar, coffee, and alcohol consumption (p < 0.05). Staphylococcus spp. was significantly enriched in non-pregnant couples, suggesting a possible negative impact on fertility. These findings suggest that the diversity of microbes in sperm can be affected by lifestyle choices and may play a role in fertility issues. This could help in the management of male infertility by changing harmful habits that might affect fertility and sperm microbiota. Further studies are needed.