In recent years, the caesarean section rate in China has been increasing year by year (50-70% in some hospitals), and a significant proportion of them are socially induced caesarean sections (pregnant women without caesarean section indications). The incidence of placenta praevia and placental implantation in second pregnancies after cesarean section has increased significantly, and the incidence of uterine incision site pregnancy, which was rare in the past, has also increased, and four cases have been found in our hospital in the past three years. The lower part of the uterus has now become a routine uterine incision for cesarean delivery, and pregnancy at the site of the uterine incision may be related to various reasons that may cause the fertilized egg to travel too fast, causing the fertilized egg to deviate from its normal position and implant in the lower part of the uterus, or when the fertilized egg reaches the uterine cavity before it is developed enough to implant, it continues to descend to the lower part of the uterus and implant there. The clinical features are painless vaginal bleeding in early pregnancy (may be irregular or sudden heavy bleeding), absence of chorionic villi and placenta discharge during medication abortion, abnormal mass in the uterine wall, persistent HCG or abdominal hemorrhage, etc. Therefore, please choose your delivery method carefully!