Association of caesarean section history with adverse pregnancy outcomes in placenta accreta spectrum: the mediating role of placenta previa

Background: Placenta accreta spectrum (PAS) is a leading cause of severe maternal and neonatal complications, yet its risk pathways remain incompletely understood. We aimed to evaluate the association between the number of prior caesarean sections (CS) and adverse maternal and neonatal outcomes in PAS, and to quantify the mediating role of placenta previa (PP) in this relationship. Methods: Based on a retrospective cohort of 231 patients with PAS (61 with no prior CS, 124 with one CS, and 46 with ≥2 CS), we performed multivariate logistic regression to assess associations between CS history and pregnancy outcomes and conducted mediation analysis to estimate the proportion of the CS effect mediated by PP. Results: Patients with ≥2 prior CS had significantly higher rates of second-trimester surgical abortion, percreta, and higher PAS severity scores. While PP, embolisation, blood transfusion, and prolonged hospitalisation were more common in women with any CS history, their frequencies did not increase proportionally with the number of CS. Multivariate analysis demonstrated that a higher number of prior CS was independently associated with increased risks of invasive PAS, massive intraoperative haemorrhage and transfusion, and preterm delivery. Mediation analysis showed that PP contributed to 8.62% of the association between CS history and invasive PAS, 16.93% for transfusion, 32.83% for preterm birth, and 11.40% for neonatal intensive care unit admission. Conclusions: A higher number of previous CS procedures in our sample was associated with higher risks of several adverse maternal outcomes in PAS. Neonatal outcomes, however, were not significantly influenced by the number of prior CS procedures and were more strongly affected by the gestational age at delivery. These relationships were partially mediated by PP, highlighting its important, but incomplete role in the pathway linking prior CS to PAS-related complications.