Study Participants
In this study, 1,446 subjects (713 in the PCOS group and 733 in the control group) were recruited from the Center for Reproductive Medicine, Shandong University, China, from March to September 2019. Basic demographic, socio-economic and life habits related characteristics were assessed using questionnaires, while the income level, vaginal douching frequency, and the frequency of sexual activity was matched between women with PCOS and healthy controls. PCOS was mainly diagnosed using Chinese Guidelines for the Diagnosis of PCOS18 based on modified Rotterdam Criteria6. PCOS diagnosis requires the presence of oligomenorrhea (menstrual cycle that lasts longer than 35 days) or irregular uterine bleeding, combined with either clinical/biochemical signs of hyperandrogenism or a polycystic ovary indicated using ultrasonography (either more than twelve follicles (2–9 mm in diameter) and/or increased ovarian volume (>10 mm3) in each ovary). Women who were diagnosed with congenital adrenal hyperplasia, testosterone-secreting tumors, Cushing’s syndrome, or other causes that result in excess testosterone were excluded. The subjects included in the control group had regular menstrual cycles (21-35 days) and no clinical or biochemical evidence of hyperandrogenemia. The exclusion criteria was antibiotic usage within one month of swab sampling, vaginal douching or vaginal medication within one week of sampling, irritation around the genital area or abnormal vaginal discharge within one week of sampling, menstruation, and sexual intercourse within 48 hours. In addition, the PCOS group was divided into PA (PCOS phenotype A) subgroup (OA+HA+PCOM, n=171) and PD (PCOS phenotype D) subgroup (OA+PCOM, n= 542). The study was approved by the Institutional Review Board of Reproductive Medicine, Shandong University. Written informed consent was obtained from all participants enrolled in the study.