Placenta grade 2 indicates that the placenta is mature. Placental maturity is divided into four grades: grade 0, grade 1, grade 2 and grade 3. grade 1 marks the basic maturity of the placenta; grade 2 marks the maturity of the placenta; grade 3 marks the aging of the placenta, due to calcification and fibrin deposition, the ability of the placenta to deliver oxygen and nutrients is reduced, and the fetus will be at risk factor at any time. In the middle 13-28 weeks of pregnancy, the placental maturity is usually at level 0; in the late 30-32 weeks of pregnancy, the placental maturity is level 1; after 36 weeks the placenta is more mature at level 2. If placenta grade 3 is found before 37 weeks, it is considered premature and needs to be alerted to the possibility of intrauterine growth retardation. placenta after 38 weeks enters grade 3, marking placenta maturity, which is normal.