PURPOSE: Lipid peroxidation may be linked with the dysfunction of endothelium of hypertensive pregnancy and it may also have effects on antioxidant response of the fetal lung. Acute change of lipid peroxidation and antioxidant enzyme activity after exposure to extrauterine environment has been shown to be involved in the pathogenesis of lung injury in preterm and term lung. We want to study the immediate postnatal possible differences between hypertensive and normal pregnancy in lipid peroxidation and antioxidant response of preterm rat lung. METHODS: Female SHR (essential hypertension, 1b, A, 6-8 weeks, n=20) Sprague- Dawley rats were cohabited. C-section was done on the 20th day of gestation to the half of pregnant SHR rats (preterm SHR group, n=50). Control group was consisted with the premature pups (preterm normal group, n=50) delivered from normal dams. The birth weight, content of malondialdehyde (MDA), and activity of superoxide dismutase (SOD) in the lung tissues were analyzed at birth and 24 hours after birth. RESULTS: Birth weights were significantly low in premature SHR group compared to control group. At birth, MDA content and SOD activity were significantly increased in preterm SHR group. After 24 hours, the MDA value and SOD activity were even more increased in preterm SHR group. CONCLUSION: These results suggest that maternal hypertension during pregnancy is associated with an increased lipid peroxidation of the fetal and immediate postnatal preterm rat lung and that compensatory activation of antioxidant system works in the fetal and newborn rat lung.