Premature birth, especially in the early weeks of pregnancy, is closely linked to perinatal morbidity and mortality. Aim: to assess the detectability and clinical significance of markers of undifferentiated connective tissue dysplasia in pregnant women at risk of preterm birth. Materials and methods. A clinical analysis of phenotypic signs of undifferentiated connective tissue dysplasia in 270 pregnant women with one baby at risk of preterm birth, which were divided into two representative groups: 1st (n=112, main group) with phenotypic signs of undifferentiated connective tissue dysplasia and 2nd (n=158, control group) without phenotypic signs. Results. Among the phenotypic signs of undifferentiated connective tissue dysplasia in pregnant women at the risk of premature birth, the most common were: asthenic body structure (38.4%), joint hypermobility (33.9%), myopia (31.3%). Stigmas of dysembryogenesis were revealed: various anomalies of the skeleton, musculoskeletal system, teeth. There was also a decrease in body mass index, indicators of the ratio of the wrist circumference to the length of the II finger, arm span to growth, heavy menstruation. 86.6% of patients showed meteorological dependence and subjective signs of respiratory syndrome. Conclusion. The obtained results allow to confirm that pregnant women with signs of undifferentiated connective tissue dysplasia are in the group of high risk of premature birth with the development of hemorrhagic complications.