Data collection
The basic information on the pregnant women was collected, including age, the times of pregnant, delivery times (≥ 28 weeks of delivery), the numbers of former caesarean, the inter-birth interval between the previous and the current caesarean section, the duration of gestation, the thickness of the uterine scar, the type of placenta previa under ultrasound (marginal, partial or complete at the front wall of the uterus) and the condition of placenta attachment (adhesion, implantation or penetration).
The data for perinatal outcomes of mother and newborn were also collected, including the termination time of the pregnancy, whether arterial blocking was applied and the related method, postpartum hemorrhage, the volume of bleeding during the delivery, blood transfusion, hysterectomy, uterine rupture, the intraoperative situation of the placenta, infection, admission to an intensive care unit, intraoperative hemostatic operations and the medicine used, the fetal biparietal diameter before delivery, and Apgar score at 1min and 5min after birth of newborns.