According to the definition of the World Health Organization, recurrent miscarriage is a consecutive three-fold spontaneous interruption of gestation (including the cessation of development). However, according to many clinicians, the presence of two episodes of pregnancy loss should be considered as the criteria for recurrent miscarriage. The prevalence of pathology is 2-5%, a significant part of the habitual losses are recorded before the viability of the fetus (22 weeks). The probability of subsequent spontaneous interruption increases significantly with an increase in the number of previous episodes: if after the first loss the risk of the next one is 15%, then after two failures in a row this figure more than doubles - up to 36-38%.