Risk Factors, Prognosis and Prediction Models for Placenta Accreta Without Prior Cesarean Section

1. Identify the risk factors for Placenta accreta spectrum (PAS) disorders in women without prior caesarean section (CS). 2. Clarify the prognostic factors of the disease and explore individualized treatment options to improve the prognosis of patients with this type of disease; 3. Use the cohort's biological sample database to conduct serology, cytology, and histology studies to explore the abnormal uterine immune microenvironment and the impact on uterine spiral artery remodeling in non-scar uterine-placenta accreta disease.