As the pregnancy progresses, the placenta can fit closely to the uterine wall after three months, at which time the fetus is stable. However, because the actual situation of each pregnant woman is different, the time of fetal stabilization cannot be generalized and has some individual differences. In the early stages of pregnancy, the placenta has not yet formed and the gestational sac is not deeply rooted in the uterus, so miscarriage can easily occur at this stage. After the third trimester, the placenta is formed and can be closely attached to the uterine wall, and the fetus is stable at this time. However, because of the special position of the placenta in some pregnant women, such as placenta praevia, marginal placenta, etc., pregnant women need to carefully protect the fetus throughout pregnancy. If a pregnant woman has unstable fetal gas, she should make a fetal preservation plan according to her own situation at this time. If the placenta is in an abnormal position, the pregnant woman can go down to the ground without signs of miscarriage, but she should be careful not to exert herself. When the signs of miscarriage occur, the pregnant woman should absolutely rest in bed and should not go to the ground.