A longitudinal study of antioxidant status during uncomplicated and hypertensive pregnancies

BACKGROUND: To study the possible involvement of an (im)balance between oxidants and antioxidants in pre-eclampsia concentrations of intra- and extracellular blood antioxidants in women with uncomplicated and hypertensive pregnancies, they were studied preconceptionally and throughout pregnancy. METHODS: In uncomplicated pregnancies (n = 19) and hypertensive pregnancies (n = 6) concentrations of whole blood and plasma thiols, plasma vitamins/E and C, hemoglobin, and hematocrit were assessed at preconception, 6, 10, 20, and 37 weeks of gestational age, as well as six weeks postpartum. A repeated mixed model was used for statistical analysis. RESULTS: Vitamin C and most whole blood and plasma thiol concentrations decreased during pregnancy, while vitamin E, whole blood oxidized cysteinyl-glycine and the ratio of free to oxidized homocysteine revealed a linear increase during pregnancy. Postpartum plasma cysteine and vitamin C levels and the ratio of free to oxidized levels of cysteine, cysteinyl-glycine, and glutathione were significantly (p <0.05) lower as compared to preconceptional levels, whereas whole blood oxidized cysteine, cysteinyl-glycine and glutathione levels, and whole blood and plasma homocysteine levels were significantly (p <0.05) higher six weeks after delivery. Plasma cysteine and homocysteine, and whole blood oxidized cysteine and homocysteine levels were significantly (p <0.05) higher at 37 weeks of gestational age in the hypertensive group compared to those in the uncomplicated group. There were no other differences between the hypertensive and uncomplicated groups. CONCLUSION: In normal pregnancy there seems a balance between antioxidant and oxidant concentrations despite modest oxidative stress. In mildly hypertensive pregnancies a marginal imbalance may occur.