A longitudinal study of antioxidant status during uncomplicated and hypertensive pregnancies

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.

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.

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.

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.