**Abstract**

The human placenta is covered with the chorionic and basal plates, which face the fetal and maternal sides, respectively. Each plate shows its own characteristics in tissue structure so that these plates would have quite different mechanical properties: The mechanical environment of the placenta would be dependent on its position, a fetal side or maternal side. In the meantime, considering that the blood circulations in the placenta, the fetal blood flows in the blood vessels, which pass through the umbilical cord, chorionic plate, and villous trees, and the maternal blood flows in the blood vessels in the basal plate and intervillous space. The chorionic and basal plates would be necessary for the fetal and maternal blood circulations, respectively. In this chapter, the influence of the chorionic and basal plates on the mechanical environment of the placenta, and the fetal and maternal blood circulations, is explained.

**Keywords:** human placenta, blood circulation, umbilical cord, villous tree, Intervillous space
