Patients
This nationwide retrospective study was performed with 747 patients recruited from 13 first-class hospitals located in the different regions of mainland China. The criteria used for patient selection was: ① previous history of cesarean section; ② cesarean delivery for this time; ③ edged, partial or complete placenta previa; placenta previa growing on the uterine scar of previous cesarean surgery. The women who had lower placenta or edged placenta previa in the posterior or lateral wall, were excluded. A hundred and six of these patients, who received uterine artery embolization or abdominal aortic balloon occlusion, were assigned to the blocking group. The other 641 women were considered as the non-blocking group.