This previous study may help to explain, in part, our present results regarding increases in placental NO metabolites, thus suggesting that high placental NO levels could be related to the NO synthesized by inducible NO synthase, an enzyme known for causing excessive NO production, but the inducible NO synthase-derived NO is inactivated by superoxide, causing oxidative stress, which may be related to endothelial dysfunction [47]. This evidence concerns the gene NOS2 and endothelial dysfunction.