Acknowledgement: the authors would like to express particular gratitude to O.M. Gavrilova, obstetrician-gynecologist at the Bryansk City Hospital № 1, for assistance in biomaterial collection.

Author contribution: Domakhina AS — search for literature, statistical analysis, manuscript writing, manuscript editing and discussion; Korsakov AV — literature review, study concept and design, interpretation of the results, approval of the final version of the article; Troshin VP — data analysis and interpretation, manuscript writing, editing and discussion; Pivovarov YuP, Korolik VV — data analysis and interpretation, manuscript editing and discussion.

Compliance with ethical standards: the informed consent to collection of biomaterial during screening and clinical data processing was obtained from all patients.