What does Placenta 1 mean?

Placental function can be divided into 0, 1, 2 and 3 grades, of which 0 and 1 are mostly born in early pregnancy, indicating that the fetus is well developed and needs adequate nutrition. 2 and 3 are mostly in the middle and late stages of pregnancy, when the placenta reaches 3, it indicates that the placenta begins to age.