The analysis of hematological parameters in premature infants with clinical signs of perinatal pathology is important and allows to assess the adaptive response of the body, especially under the conditions of negative eff ects of hypoxia. Almost half of all preterm births are caused by infl ammatory processes in the mother leading to rupture of membranes with or without chorioamnionitis. Due to the functional immaturity of organ systems and regulatory mechanisms, preterm infants have certain problems of adaptation in the neonatal period. Disruption of a balanced adaptive response to changing environmental conditions due to dysregulation of immune defense and immunosuppression is the basis for the initiation of pathophysiological mechanisms of hypoxic stress and damage to the body, starting from the subcellular level. This causes severe dysmetabolic changes with the formation of serious diseases with a high risk of mortality and the formation of long-term consequences of pathology in survivors, reducing the quality of life of patients in later years. Materials and methods. We studied 68 infants with a gestational age of 32 to 33/6 weeks who had clinical signs of perinatal pathology (main study group). Subgroup A included 35 newborns with severe disease, and subgroup B included 33 children whose general condition was considered moderate. The comparison group consisted of 31 infants with a gestational age of 34 to 36/6 weeks (control group). Inclusion criteria were confi rmed clinical signs of moderate and severe perinatal pathology; exclusion criteria were gestational age at birth less than 32 weeks and 37 weeks or more, congenital malformations. A comprehensive clinical and laboratory examination of newborns was performed, considering the main and concomitant pathology.Based on the results of the complete blood count, the ratio of indicators was calculated: NLR (neutrophil to lymphocyte ratio), PLR (platelet to lymphocyte ratio), MLR (monocyte to lymphocyte ratio); as well as SII (systemic immune infl ammation index); SIRI (systemic infl ammation response index); PIV (platelet, neutrophil, monocyte and lymphocyte index). Taking into account the data obtained, the risk of deterioration of newborns’ condition in relation to perinatal risk factors was identifi ed, the limits of indicators and indices of systemic hypoxic infl ammation in relation to moderate and severe pathology were determined.Scientifi c research was conducted in accordance with the basic provisions of GCP (1996), the Convention of the Council of Europe on Human Rights and Biomedicine (April 4, 1997), the Declaration of Helsinki of the World Medical Association on the Ethical Principles for Research on Human Subjects (1964-2008), Order of the Ministry of Health of Ukraine No. 690 dated September 23, 2009 (as amended by Order of the Ministry of Health of Ukraine No. 523 dated July 12, 2012). Protocol of scientifi c research of the Biomedical Ethics Commission of BSMU dated September 12, 2015. Considering the complex subject of the research work, the informed consent of the parents of newborns was obtained after familiarization with the purpose, objectives and planned methods of laboratory and functional studies. Statistical processing of results was performed using STATISTICA software (StatSoft Inc., USA, version 10). Comparison of quantitative indicators with normal distribution was performed using Student’s t-test, and the probability of diff erences was consideredstatistically signifi cant at p<0.001.Results of the study. The results of the study showed that in order to determine the severity of the general condition in premature infants, along with the assessment of clinical signs of pathology, it is advisable to conduct a detailed analysis of the results of a complete blood count with the study of the ratio of individual indicators and the determination of systemic infl ammation indices. This allows to improve the approaches to diff erential diagnosis of the severity of neonatal diseases by using a low-cost conventional method, while obtaining more correct conclusions. The indicators of complete blood count in newborns confi rm the presence of compensatory activation of erythroid, myeloid and granulocytic hematopoiesis in response to hypoxia in the early neonatal period. The obtained data showed signifi cant diff erences from the control values, which correlated with the severity of the newborns’ condition. Reserves for improving the eff ectiveness of medical care for IPA should include the improvement of diagnostic measures to clarify the pathophysiological mechanisms of hypoxic infl ammation in order to reduce mortality and prevent the development of long-term consequences of the pathology, while maintaining the health and quality of life of patients.Conclusions:1. Determination of the ratio of GBT and systemic infl ammatory indices can be a qualitative adjunct to diagnosis to clarify the pathophysiological mechanisms of hypoxic damage to the body and to objectify approaches to assessing the severity of the condition of newborns with various forms of perinatal pathology.2. The risk of worsening in children with development of moderate pathology should be predicted at the following limits of the ratio of indicators: an increase in NLR from 0.295 to 0.343, a decrease in PLR from 7.982 to 7.290 and MLR from 0.096 to 0.093; an increase in systemic infl ammation indices: SII – from 66.546 to 76.386, SIRI – from 0.802 to 0.975, PIV – from 180.825 to 225.130.3. Severe course of diseases in newborns is predicted on the basis of ratio of indicators: NLR – up to 0.238, PLR – up to 5.923, MLR – up to 0.086 and the presence of systemic infl ammation indices: SII – up to 51.230, SIRI – up to 0.745 and PIV – up to 160.310.