Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects up to 10% of the reproductive-aged women worldwide. The etiology is still unknown and treatment therefore remains symptomatic. Studies indicate a possible role of the gut microbiome in the pathology of PCOS. PCOS women have a disturbed gut microbiome, with certain species associated with the PCOS characteristics:hyperandrogenism, ovarian dysfunction, obesity, glucose intolerance and insulin resistance. Although differences have been found in gut microbiome composition between PCOS and healthy women, the literature is inconclusive regarding the difference in gut microbiome biodiversity. Studies examining the vaginal microbiome in PCOS women show consistent results with specific species in the vaginal microbiome. However, there are only few studies on the vaginal microbiome in PCOS women and no studies have yet investigated the correlation between sex-specific hormones and PCOS characteristics. More research is needed to understand the function of the microbiome in the pathophysiology of PCOS, so that this can offer perspectives in future therapies.

Inclusion criteria

• Caucasian
• Willing to provide vaginal swab and stool sample
• Willing to provide informed consent
• Sufficient command of the Dutch language
• Diagnosed with PCOS at Erasmus MC using the Rotterdam criteria by the presence of at least two of the following criteria
• Clinical or biochemical hyperandrogenism (modified Ferriman-Gallway score >5; testosterone level >2nmol/L, Free Androgen Index > 2.9)
• Oligomenorrorrhea or amenorrhea
• Polycystic ovaries.

Exclusion criteria

• BMI <18
• Smoking
• Diabetes Mellitus or use of insulin sensitizer
• Chronic and acute infection diseases
• Endometriosis (American Fertility Score (AFS) III/IV)
• Elevated prolactin levels, thyroid disease, Cushing disease or gastro-intestinal disease
• The use of hormonal contraceptives, and other steroid hormones in the last 3 months
• Use of antibiotics, probiotics or laxatives in the last 3 months

Patients at the outpatient clinic of Reproductive Medicine.