Selenium (Se), an essential trace metal, is important in both growth and reproduction and is the constituent of different selenoproteins. The glutathione peroxidase (GPx) family is the most studied as it prevents oxidative stress. Liver oxidation is considered as another mechanism involved in low birth weight. Therefore, in order to ascertain whether GPx is related to the effects of Se on growth during gestation and lactation, three groups of rat pups were used: control, Se deficient (SD), and Se supplemented (SS). Morphological parameters and reproductive indices were evaluated. Hepatic Se levels were measured by graphite furnace atomic absorption while spectrophotometry was used for activity of antioxidant enzymes and oxidative stress markers in liver and western blotting for expression of hepatic GPx1 and GPx4. The SD diet increased mortality at birth; decreased viability and survival indices; and stunted growth, length, and liver development in offspring, thus decreasing hepatic Se levels, GPx, glutathione reductase, and catalase activities, while increasing superoxide dismutase activity and protein oxidation. The SS diet counteracted all the above results. GPx1 expression was heavily regulated by Se dietary intake; however, although Se dietary deficiency reduced GPx4 expression, this decrease was not as pronounced. Therefore, it can be concluded that Se dietary intake is intimately related to growth, length, and directly regulating GPx activity primarily via GPx1 and secondly to GPx4, thus affecting liver oxidation and development. These results suggest that if risk of uterine growth retardation is suspected, or if a neonate with low birth weight presents with signs of liver oxidation, it may be beneficial to know about Se status.