The position of the placenta should be greater than 5 cm from the inner cervical opening to be considered normal. If the placenta is less than 5 cm from the internal cervical os, it is considered to be hypoplastic. If it covers the edge of the cervical os, it is a borderline placenta praevia. In general, the position of the placenta can be fixed after 28 weeks. Before 28 weeks, if the position of the placenta is low, you should try to pay attention to not standing for a long time and should pay attention to bed rest. If the placenta is still low after 28 weeks, you should pay attention to the fact that you should not have sex or overwork during this period, otherwise it will easily lead to rupture and bleeding of the placenta praevia. The low position of the placenta can cause frequent bleeding and, if serious, can easily lead to hemorrhagic shock.