Placenta grade 3 at 36 weeks of pregnancy is normal and pregnant women should not be overly nervous. Placenta from the process of occurrence, growth, development, maturity, aging is divided into four grades, that is, 0-3, 28 weeks before the placenta is 0; 28-36 weeks for 1; 36-40 weeks for 2-3, pregnant women are 36 weeks, the placenta level 3 belongs to the normal state. The placenta is between the mother and the fetus, consisting of the fundic meconium, the leafy chorionic villus and the amniotic membrane. In addition to the exchange of substances between the mother and the fetus, the placenta also has the functions of barrier, immune regulation of the endocrine secretion and the synthesis of a variety of cytokines, enzymes and other biologically active substances, but the barrier effect of the placenta is relatively limited.