Comparative Study to Evaluate the Efficacy and Safety of the Fixed-dose Combination of Estradiol / Dydrogesterone in Perimenopausal Women

Inclusion Criteria: 1. Caucasian women in perimenopause (STRAW -1/ +1a) with an intact uterus. 2. Age from 40 to 55 years old as of the time of screening. 3. Absence of natural menstruations within 4 months, but not longer than for 12 months. 4. 50 or more episodes of "hot flashes" in the last 7 days according to the patient diary (at the screening). 5. Patients scoring more than 12 points on the Greene Scale. 6. Follicle-Stimulating Hormone (FSH) levels more than 25 IU/L, estradiol levels less than 190 pmol/L. 7. Consent to the use of barrier methods of contraception. 8. Body mass index \<30 kg / m2. 9. Signed Informed Consent Form. 10. Mammography performed within 6 months prior to inclusion in the study. 11. Absence of clinically significant deviations according to the results of medical examination: physical examination (including assessment of the state of the mammary glands), measurement of indicators of vital body functions (blood pressure, heart rate, respiratory rate and body temperature) and gynecological examination. 12. The patient's consent to perform all research procedures and adhere to all restrictions provided for by the research protocol. Exclusion Criteria: 1. Smoking. 2. Administration of drugs from the prohibited therapy list. 3. Known hypersensitivity to estradiol, dydrogesterone, to the active component of the drug Klimadynon® (dry extract of rhizomes of cimicifuga racemose) or to any of the excipients of the study drugs. 4. Pregnancy and breastfeeding. 5. Abnormal uterine bleeding from the vagina of unclear etiology within 12 months before the screening stage. 6. Breast cancer (diagnosed, suspected, or past). 7. Estrogen-dependent malignancies of the sex organs, including endometrial cancer (diagnosed, suspected, or past). 8. Known or suspected progestogen-dependent neoplasms (e.g. meningioma). 9. Untreated endometrial hyperplasia. 10. Venous and arterial thrombosis/thromboembolism, currently or in history (including deep vein thrombosis, pulmonary embolism, myocardial infarction, ischemic or hemorrhagic stroke; angina pectoris, transient ischemic attack). 11. Diagnosed hereditary or acquired predisposition to arterial or venous thrombosis/thromboembolism (eg, hyperhomocysteinemia, deficiency of protein C, protein S or antithrombin III, the presence of antiphospholipid antibodies). 12. Acute or chronic liver disease in history (in case of deviation from a norm of liver function indicators); benign and malignant liver tumors (including hemangioma, adenoma, liver cancer) or an increase in Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST) activity detected during screening by more than 1.5 times relative to the upper limit of normal. 13. Porphyria. 14. Epilepsy. 15. Brain disorders and traumas. 16. Galactose intolerance, lactase deficiency, glucose-galactose malabsorption syndrome. 17. Cholestatic jaundice and/or severe cholestatic itching (especially during a previous pregnancy or sex hormone intake). 18. Uncontrolled hypertension. 19. Diabetes mellitus. 20. Adenomyosis grade \>3 and uterine myoma (more than 3 nodes with an intermuscular or subserous arrangement with a diameter of more than 3 cm) and / or centripetal growth/submucous node location. 21. Cholelithiasis. 22. Systemic lupus erythematosus. 23. Bronchial asthma. 24. Otosclerosis. 25. Known renal or hepatic insufficiency. 26. Ovarian cysts \>6 mm based on results of ultrasound scanning. 27. Endometrial thickness ≥5 mm according to transvaginal ultrasound. 28. Migraine headache or a history of severe migraine-type headaches. 29. Other medical conditions which could interfere with the study-related procedures and/or influence the efficacy of the study drug. 30. Simultaneous intake of excluded drugs. 31. Participation in any other clinical study within 3 months before screening. 32. Pathological result of smear for cytology (PAP test) and Human papillomavirus (HPV) test. 33. The use of estrogens or combination drugs for hormone replacement therapy (HRT) within 6 months before the start of the study. 34. Higher risk of thromboembolic complications due to prolonged immobilization for 2 weeks before the screening stage (for example, as a result of trauma or surgery). 35. Previous major surgical interventions (including abdominal) within 6 months before the start of the study. 36. Tumor of the pituitary gland. 37. Severe pathology of the cardiovascular system: complicated lesions of the valvular apparatus of the heart, uncontrolled drug arrhythmia, chronic heart failure I - IV functional class. 38. Sickle cell anemia. 39. Congenital hyperbilirubinemia (Gilbert, Steven-Johnson and Rotor). 40. A history of pancreatitis with severe hypertriglyceridemia. 41. Polyp in the uterine cavity. 42. Use of any drugs in the form of prolonged-release injections or implants within 3 months before the screening stage. 43. A history of any other malignant neoplasms within 5 years prior to the study, with the exception of adequately treated squamous cell skin cancer. 44. Anamnestic data on any clinically significant disease of the kidneys, lungs, gastrointestinal tract, skin and subcutaneous tissues, musculoskeletal system, blood and lymphatic system, nervous system. 45. Positive blood test for HIV, hepatitis B and C, syphilis. 46. Alcoholism, drug addiction in history. 47. Prior endometrial ablation therapy.