Randomized, controlled, double-blind, three-arm clinical trial in which 75 women will be randomized to treatment with metformin, 75 women to treatment with placebo and 50 women to the observation group. The medical intervention will last 24 weeks (6 months). Women with confirmed idiopathic infertility, in whom infertility factors have been excluded during full diagnostics, will be included in the study

Inclusion Criteria:

1. Age 18-45
2. No pregnancy for a minimum of 12 months prior to screening.
3. Diagnosed with idiopathic infertility.
4. No use of hormone therapy 30 days before screening.
5. No use of any methods of contraception 30 days before screening and during the examination.
6. BMI between 18.5 - 30 kg/m2.

Exclusion Criteria:

1. Positive pregnancy test result.
2. Patients diagnosed with another factor of infertility.
3. Patients with type I or II diabetes.
4. Patients taking metformin or other hypoglycaemic drugs in the last 4 weeks before screening.
5. Patients with hepatic impairment and abnormal liver function tests (alanine aminotransferase and/or aspartate aminotransferase (above 3x ULN).
6. Patients with an eGFR less than 45 mL/min/1.73m2.
7. Accompanying chronic diseases with poor prognosis.
8. Patients with a history of lactic acidosis or other metabolic acidosis.
9. Patients with a history of congestive heart failure III/IV NYHA degree.
10. Patients with acute myocardial ischemia.
11. Patients with sepsis or severe infection.
12. Diseases which, in the opinion of the investigator, constitute an exclusion criterion and prevent the patient from participating in the study.
13. Patients with predictable problems with cooperation with the research team.