Introduction Microbiome composition across multiple body sites, including the vagina, gut, urinary tract and semen, has been implicated in reproductive health and infertility. Vaginal dysbiosis and reduced Lactobacillus abundance have previously been associated with poorer outcomes in assisted reproductive technologies, yet few studies have simultaneously characterised microbiomes of both partners or compared infertile couples with healthy population controls. The BIOME study, a prospective cohort study, aims to characterise multisite microbiomes in infertile and healthy Danish couples and examine their association with long-term fertility outcomes. Methods and analysis The BIOME study is a multicentre, prospective observational cohort study including 100 couples undergoing fertility treatment following ≥12 months of unsuccessful pregnancy attempts and 100 healthy control couples. Participants provide biological samples from multiple body sites (vaginal swab or semen, faeces, urine and blood) prior to initiation of fertility treatment. Samples will undergo microbial sequencing, quantitative PCR, culture-based analyses, proteomics, metabolomics and microRNA profiling. Questionnaire data, clinical information and electronic medical record data will be collected. Participants will be followed for 5 years after sample collection to assess fertility outcomes. No intervention, randomisation or blinding is performed. Recruitment is planned over 24 months. Ethics and dissemination The study has been approved by the Danish Ethics Committee (#SJ-1033), and all participants provide written informed consent. Data are processed according to the General Data Protection Regulation and the Danish Data Protection Act, with pseudonymisation and restricted-access procedures. Results will be disseminated through peer-reviewed publications and scientific conferences. Sequencing data will be deposited in a public repository (eg, European Nucleotide Archive) with personal identifiers removed, and curated metadata will be available on reasonable request.
Storck-Thy et al. (Fri,) studied this question.