Background: Preeclampsia (PE) is a pregnancy-induced syndrome associated with increased maternal and fetal morbidity and mortality. The major fetal consequences of PE are intrauterine growth restriction and premature delivery. It is hypothesized that placental oxidative stress results in shedding of circulating factors into the maternal circulation, leading to endothelial dysfunction and inflammation in the maternal circulation. This mediates the maternal characteristics of PE; hypertension and proteinuria. There are conflicting reports as to what extent fetal circulation is involved. Oxidative stress is a condition where prooxidants dominate over antioxidants. Several studies have associated PE with augmented oxidative stress. 8-isoprostane is a stable marker of oxidative stress; it is formed by free radicals attack on arachidonic acid in cell membranes phospholipids. The aim of this study was to compare the level of oxidative stress in both maternal and fetal circulation in PE and uneventful pregnancies.
Methods: Maternal venous blood samples were obtained before cesarean section from 25 PE and 39 uneventful pregnancies. Umbilical cord blood samples were obtained separately from umbilical vein (16 PE, 34 controls) and arteries (15 PE, 21 controls). Total 8-isoprostane concentrations were measured with GC-MS, and antioxidants evaluated as FRAP(ferric reducing ability of plasma) and vitamin E.
Results: The median level of total 8-isoprostane in plasma was significantly higher in maternal circulation in PE compared to controls (404 pg /ml vs 207pg /ml, p=0.003). Median FRAP concentration was 26% higher in the PE group, vitamin E levels did not differ between the groups.The median level of 8-isoprostane in the umbilical vein was high, but there was no difference between PE and controls (955 pg /ml vs 801 pg /ml, p= 0.52). No difference in umbilical artery 8-isoprostane concentrations was found between the groups (233 pg /ml vs 276 pg /ml, p= 0.65). In the umbilical vein, both median FRAP and vitamin E concentrations was higher in the PE group. In the umbilical arteries, median FRAP concentration was higher in the PE group, but no difference was found in median vitamin E levels.
Conclusion: This study confirms increased oxidative stress in maternal circulation in PE. In the fetal circulation, we found no difference between PE and control group, but the concentration of 8-isoprostane delivered to the baby from the placenta was high, whereas blood from the baby had a much lower 8-isoprostane concentration.
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Braekke, K., Harsem, N. & Staff, A. 39 Is There Evidence of Oxidative Stress in Maternal and Fetal Circulation in Preeclampsia?. Pediatr Res 56, 470 (2004). https://doi.org/10.1203/00006450-200409000-00062