The transient increase of oxidative stress during normal pregnancy is higher and persists after delivery in women with pre-eclampsia

Objectives: Glutathione, an intracellular tripeptide, functions in the protection of cells against free radicals and toxins of endogenous and exogenous origin. To maintain the intracellular redox status in presence of reactive oxygen species, glutathione (GSH) and other thiols are oxidized. The oxidative status of thiols is reflected by the free-to-oxidized ratio and is a real-time measure for oxidative stress. Previously, we have reported abnormal ratios for the thiols cysteine (Cys), homocysteine (Hcy) and cysteinylglycine (CysGly) in women with pre-eclampsia. The aims of this study were to confirm our previous findings in a different case-control cohort and more importantly to determine whether these differences persist postpartum. Study design: At onset of disease and at 6-8 weeks postpartum we analyzed whole blood of 41 women with pre-eclampsia and of 31 women with normotensive pregnancies for the free-to-oxidized ratio of thiols by the assessment of free and oxidized thiol levels using high performance liquid chromatography. Differences between values were determined using either the paired t-test (antepartum versus postpartum) or the t-test (pre-eclampsia versus normotensive pregnancy). Results: Antepartum levels of free GSH as well as the free-to-oxidized ratios of Hcy were lower in pre-eclampsia and normotensive pregnancy when compared with corresponding postpartum values (P < 0.0001 and P < 0.01, respectively). Moreover, the free-to-oxidized ratio for Hcy was significantly lowered in pre-eclamptic compared with normotensive women, during as well as after pregnancy (both P ≤ 0.01). Conclusion: The data suggest that pregnancy is a state of higher oxidative stress when compared to the postpartum period. In women with pre-eclampsia, oxidative stress is higher and persists in the postpartum period.