This multicenter, institution-based, cross-sectional study evaluates the prevalence of polycystic ovary syndrome (PCOS) and PCOS phenotype in Eastern Siberia - the unique region of the Russian Federation with a multi-raced population living in similar geographic and socio-economic conditions for centuries. Therefore, the investigators considered this population optimal for epidemiological research.

Polycystic Ovarian Syndrome (PCOS) has a high prevalence and is a significant reproductive, metabolic, and psychosocial disorder. Several studies have demonstrated that PCOS affects from 6% (defined by NIH 1990 criteria) to 19.5% (under Rotterdam 2003 criteria) of reproductive-aged women (Jalilian et al., 2015; Bozdag et al., 2016). The prevalence of PCOS and its symptoms may vary according to geography and race/ethnicity (Huang et al., 2016; Ding et al., 2017). Clinical studies indicate variations in the presence and severity of PCOS and its clinical symptoms: hirsutism, obesity, insulin resistance by race and ethnicity. Unfortunately, there is a lack of data on the prevalence of PCOS and its phenotype in many geographic regions, in particular, in one of the largest countries in the world, Russia.

Objectives: To determine the prevalence of PCOS and the PCOS phenotypes in unselected (medically unbiased) premenopausal women in the Eastern Siberia region.

Study design and population: this is the multicenter, institution-based, cross-sectional Eastern Siberia PCOS Epidemiology & Phenotype (ESPEP) Study, conducted in Irkutsk Region and the Burjat Republic (Russia) during 2016-2019 yrs. ESPEP included premenopausal women aged 18 to 44 yrs, Caucasians, Asians, or those of mixed-race, recruited during an obligatory early medical employment assessment, and provided written informed consent. The study is approved by the Institutional Ethics Committee of the Scientific Center for Family Health a Human Reproduction (Irkutsk, Russian Federation).

Methods. Subjects are evaluated consecutively, including questionnaires, anthropometry, and vital signs, gynecological examination, modified Ferriman-Gallway (mF-G) scoring, pelvic ultrasound, and blood sampling. For PCOS diagnosis the investigators use the Rotterdam (2003) criteria. Serum samples are analyzed for total testosterone (TT) using LC-MS/MS. DHEAS, sex hormone-binding globulin (SHBG), prolactin, TSH, and 17-OHP are assessed by ELISA. Free Androgen Index (FAI) is calculated (i.e. [TT/SHBG] x 100). The upper normal limit (UNL) for the mF-G score is determined using a 2k-cluster analysis in the total study population. The upper normal limits (UNL) for TT, FAI, and DHEAS are determined from the 98th percentiles for these parameters in )women, identified as the "super-controls". Pelvic ultrasound (U/S) is performed by 3 experienced specialists with the appropriate intra/inter-observer variations, using Mindray М7 (MINDRAY, China), a transvaginal probe (5,0-8,0 МHz) or transabdominal probe (2,5-5,0 MHz). Ovarian volume is determined by the following formula: length x width x height x 0,523.

Inclusion Criteria:

• Signed and dated informed consent form
• Willing to comply with all study procedures and be available for the duration of the study
• Female
• Aged 18 to 44
• All races and ethnic backgrounds

Exclusion criteria:

• Current pregnancy or lactation
• History of hysterectomy, bilateral oophorectomy, endometrial ablation, uterine artery embolization
• Current or previous (within 3 months) hormonal medications or insulin-sensitizers intake
• Anything that would place the individual at increased risk or preclude the individual's full compliance with or completion of the study
• Unwillingness to participate or difficulty understanding the consent processes or the study objectives and requirements

An unselected women from Eastern Siberia aged 18 to 44 years, Caucasians, Asians, or women of mixed race, recruited in Irkutsk Region and the Burjat Republic (Russia) during an obligatory early medical employment assessment in 2016-2019.

For continued research, IPD data from the ESPEP study will be available to other researchers who have developed important research questions that can be answered by these valuable data. This data access policy applies to all individuals or organizations who would like to utilize data from the ESPEP Study.

ESPEP study data may be requested by researchers from various institutions for research purposes only, by submitting an expression of interest (EoI), which should include brief information about a Project leader's name, institution, a title of the potential project, and ethical approval from the Ethics Committee, and a summary of the proposed project.

IPD to be shared may include de-identified socio-demographic, clinical data, as well as lab tests results

The data is currently available, without time limitations

Requests for access to data will be reviewed by the Sponsor and the Steering Committee of the ESPEP study A Statement of Data Use and a Confidentiality Statement must be signed by any person associated with the project including those who present results, or whose name appears on a publication that is associated with the project. Data access will not be granted until these documents are signed.

In signing the Statement of Data Use the lead researcher acknowledges responsibility for ensuring adequate facilities and resources to enable the project to progress in a reasonable manner. Full acknowledgment of the source of data used must be provided in any publications that arise from access to and use of the data as set out in the publication policy