The placenta is composed of 3 main parts: the fetal part is the amnion and the lobulated chorion, and the maternal part is the fundus mater. The amniotic membrane is the closest surface of the placenta to the fetus, the surface of the amniotic membrane is smooth, without blood vessels and nerves, and the thickness of the amniotic membrane is very thin, only 0.02-0.05mm. the lobulated chorionic membrane is the most important part of the placenta, the exchange of nutrients and oxygen between the fetus and the mother, and the discharge of metabolic waste from the baby are all carried out in the lobulated chorionic membrane of the placenta. The weight of a normal full-term placenta is between 450-650g, and the surface area of the chorionic membrane of a full-term placenta can reach 12-14m^2, which is equivalent to the total area of the adult intestine. The blood of the fetal baby and the mother’s blood are not directly connected because of the barrier effect of the placenta. The bottom meconium is the endometrium at the site of placental attachment, and this makes up only a very small part of the placenta.