Total hydroperoxide (TH), free radical-mediated oxidation product can be used as a measure of free radical injury. The aim of the present study was to see if preterm newborns are at increased risk for oxidative stress compared with term newborns, and to determine whether oxidative stress during postnatal first 1 week is associated with clinical outcomes in preterm infants.

Serum TH levels of preterm infants (n=39) were compared with those of term infants (n=24) on the postnatal day 1. Among the preterm infants, serum TH levels of uncomplicated group (n=23) were also compared with those of complicated group (n=16) who developed oxygen radical related diseases on the postnatal day 1 and 7. Retrospective analysis was performed to find out risk factors for oxygen radical injuries based on birth history, laboratory data, neuroimaging findings and clinical progress in two preterm groups.

Serum TH levels on postnatal day 1 were higher in the preterm infant group than the term infant group. Serum TH levels on postnatal day 1 in the complicated preterm infant group were significantly higher compared with uncomplicated group, but there was no significant difference in serum TH levels on postnatal day 7. Also, there was no significant difference in serum TH levels between uncomplicated preterm infants and term infants. Serum TH level on postnatal day 1 was independently associated with higher morbidity after adjusting for gestational age, Apgar score (5 min), arterial blood gas analysis.

Complicated preterm newborns are at increased risk for oxidative stress compared with uncomplicated newborns and term newborns. Oxidative injury during the prenatal or postnatal day 1 is associated with adverse outcomes in preterm infants. Elevated TH levels on postnatal day 1 may have a value to predict clinical outcomes in preterm infants.