Aim To determine clinico-diagnostic significance of peroxynitrite content in the blood serum of the umbilical cord in babies with cerebral ischaemia (CI) of different severity.

Methods 45 babies with perinatal hypoxic-ischaemic brain injury were examined: 23 babies with CI of the 1^st degree (group 1) and 22 newborn babies with CI of the 2^nd and 3^rd degrees (group 2). The control group was comprised of 15 healthy babies, who were born by women with physiological course of pregnancy and labour. The material was the blood serum of the umbilical cord received by means of centrifugation. The concentration of peroxynitrite was determined by spectrophotometry. Statistical treatment of data was performed with the help of Statistica-6 program with the use of basic techniques of descriptive statistics and nonparametric techniques (Mann-Whitney U-test and Wilcoxon rank sum test).

Results In the patients of the group 1 with CI of the 1^st degree the content of peroxynitrite in the blood serum did not differ from the control values (p > 0.05), while in the newborn babies of the group 2 with CI of the 2^nd and 3^rd degrees there was a significant increase of the given index in the umbilical cord blood (p < 0.05).

Conclusions The determination of peroxynitrite content in the blood serum of the umbilical cord, which has strong oxidant properties and is able to destroy cellular structures and cause apoptosis, can serve as an objective biochemical marker of the brain damage severity in newborn babies and hence it can be a criterion for the choice of therapeutic measures.