High placenta position is normal in clinical practice and has no adverse effects on the mother, fetus and delivery process. Low placenta position can be divided into four types: complete placenta praevia, partial placenta praevia, marginal placenta praevia and low placenta according to the relationship between the lower edge of the placenta and the inner cervical opening, which have adverse effects on mother and child. The lower edge of the placenta is not less than 2cm from the endocervix. the uterus is soft, clear outline, no pressure pain, the size of the uterus matches the gestational week, and the fetal position is clear. Low placental position 1. Clinical manifestations: recurrent painless vaginal bleeding without any cause in late pregnancy or at the time of labor; 2. Ultrasound examination: after 28 weeks of pregnancy, the lower edge of the placenta is less than 2cm from the inner cervical opening, or even the lower edge of the placenta reaches or covers the inner cervical opening, and its position is lower than the fetal previa. The effect on mother and child 1. high placenta position: no adverse effect; 2. low placenta position: (1) postpartum hemorrhage (2) preterm delivery with implanted placenta (3) anemia puerperal infection (4) poor prognosis of perinatal baby puerperal infection 4. prevention of low placenta position 1. take active and effective contraceptive measures; 2. avoid multiple births, multiple scraping or induction of labor and cesarean section; 3. women planning pregnancy should quit smoking and avoid passive smoking. Smoking.