Changes of lipid peroxidation and superoxide dismutase activity in the human placenta

The oxygen radical may induce peroxidation of unsaturated fatty acids in vivo. We studied changes in superoxide dismutase (SOD) activity and lipid peroxidation using human placental tissue. Lipid peroxidation was marked in early stages (2 to 4 months) of gestation but decreased with growth and was very small by the end of pregnancy. The SOD activity of placental tissue in early gestation was approximately 250 to 500 U per gram of wet weight. The activity increased with growth of the placenta and reached a level of 400 to 1,500 U per gram of wet weight by the end of gestation. These results for SOD activity suggest that the oxygen requirement in the placenta at early stages of gestation is low compared with that at the end of gestation.