Prooxidant-antioxidant balance in pregnancy: a randomized double-blind placebo-controlled trial of selenium supplementation

Objective: We assessed the impact of selenium, a trace element with antioxidant properties on a simple measure of oxidative stress in pregnant women. Study design: A novel assay of prooxidant-antioxidant balance (PAB) was applied in a double-blind, placebo-controlled study of selenium supplementation in pregnancy. We measured the prooxidant burden and the antioxidant capacity simultaneously in one assay, thereby calculating a redox index. A total of 166 primigravid pregnant women in the first trimester of pregnancy, were randomized to receive 100 mu g of selenium (n=83) or placebo (n=83) per day until delivery. PAB values and serum selenium concentrations were measured at baseline and at the end of study. Results: Pretreatment demographic data and biochemical indices including serum selenium concentrations did not differ significantly between the groups. The drop-out rates for the groups were 22/83 and 19/83 for the selenium and placebo groups, respectively. Supplementation with selenium was associated with a significant increase in mean serum selenium concentration (P<0.001) but without significant change in mean PAB value. In contrast, mean serum selenium concentration remained unchanged and mean PAB values increased significantly (P<0.05 in the control group). Conclusion: Our findings suggest that selenium supplementation may reduce oxidative stress associated with pregnancy.