Generally, it takes about 2 weeks for the placenta to mature from degree 2 to degree 3, but there are specific individual differences. The time of placental maturation from 2nd degree to 3rd degree is not fixed, usually about 2 weeks, and it is related to the nutrition and calcium intake of pregnant women and other factors. The second degree placenta is the mature stage of placenta, mostly appearing around 36 weeks of pregnancy, but some pregnant women still have the second degree placenta until delivery, and can also carry out delivery. At this time, the placenta is mature and tends to be aging, the ability of the placenta to transport nutrients and oxygen can be significantly reduced, the function of material exchange is weakened, and the fetus will be in danger at any time. Therefore, if a third degree placenta occurs, the pregnancy should be terminated in time to avoid fetal distress and other situations. It is recommended that pregnant women should check the fetal heartbeat, fetal movement and placental maturity in time to prevent the placenta from aging and causing danger to the fetus.