The position of the placenta changes, and as the weeks of pregnancy increase and the uterus grows, the placenta will follow the uterus and become larger. Some people have a low placenta position when they have an NT ultrasound at 12 weeks in early pregnancy, but when they have a major ultrasound later in the pregnancy, or a full-term ultrasound at 37 weeks, the placenta is found to be in a normal position. Low placenta refers to after 28 weeks of pregnancy, the position of the placenta, the part of the fetal prenatal exposure, and the relationship with the inner mouth of the cervix are different, and is divided into four types, the most dangerous is complete placenta previa. The most dangerous is complete placenta. Low placenta means that the placenta is attached to the lower part of the uterus, and the lower edge of the placenta is less than 2cm from the endocervical opening. Whether it’s complete placenta praevia or low placenta, it can’t be tried vaginally, and cesarean section is needed.