Background: The intensive implementation of molecular cytogenetic technologies into medical practice has made it possible to detect genomic rearrangements with previously unavailable resolution (molecular karyotyping), including premature and low weight babies. However, such studies in these groups of children have never been carried out, and the relationship of their birth with various developmental disorders and genomic anomalies is yet to be studied. The aim of the study: The research objective is to study a group of children with low birth weight and various developmental disorders, born before 37 weeks of gestation, Materials and methods: Cytogenetic and molecular cytogenetic studies of genome variations in the group of 52 children born between 26-37 weeks of gestation with small body weight, facial dysmorphisms and congenital malformations were performed. For correct interpretation of the phenotypic consequences of genomic variations the results were analyzed with the use of the previously described bioinformatic technology. Results: 96.15% of premature babies with congenital malformations and facial dysmorphisms, and later demonstrating a psychomotor development delay, were diagnosed with various genomic disorders, therefore suggesting a role of these disorders in clinical manifestations and their possible significance for premature birth. The cytogenetic study revealed numerical and structural chromosome abnormalities in 11.5% of cases. Mosaic genomic abnormalities, co-occurring with regular rearrangements, were found in 25%. Genomic deletions and duplications were found in almost the same proportion. The X chromosome exhibited the largest number of rearrangements (30.8%) among other chromosomes. Genomic variations, including combined rearrangements, were found in 19 of 52 (36.5%) patients with congenital heart defects, in 7 children (13.5%) with autism spectrum disorders; in 8 children (15.4%) with epilepsy (convulsions/seizure patterns), in 10 individuals (19.2%) with nephrologic disorders. Almost all patients demonstrated psychomotor development disorders further in life. Conclusion: In all children under the study, the bioinformatic analysis, based on the use of gene prioritization, has revealed a large number of genes (about 1500) associated with the clinical picture, with FMR1 gene [OMIM: 309550] as the most frequent. The variability of clinical and molecular results of this study does not yet allow us to make correct comparisons of the pathological significance of genomic disorders related to premature and low weight babies. Both the obtained data and analysis can demonstrate the viability and long-term benefits of the studies aimed at solving the problems of prematurity.