What does marginal umbilical cord entry mean?

When doing color Doppler ultrasound, if the marginal umbilical cord entrance is found, that is to say, the root of the umbilical cord is attached to the edge of the placenta, and the normal umbilical cord root is attached to the center of the placenta or some positions slightly offset, this is a normal phenomenon. If the umbilical cord is attached to the edge, especially to the fetal membrane, there is a certain risk. First, if it is attached to the edge, its blood supply will be poor, which may cause the baby's growth to be limited. Its nutrition and oxygen will be reduced. Especially if some fetal membranes are attached, sometimes even some previa blood vessels will be formed. This risk is even greater. The so-called previa blood vessels are some blood vessels of the umbilical cord that are connected to the placenta through the fetal membrane. And this blood vessel is located at the cervix, in front of the fetal presentation, so when the rupture of the fetal membrane occurs, there may be some risk for the baby.