Association between congenital uterine anomalies and placenta accreta spectrum: an exploratory retrospective observational study

Objective To investigate the association between congenital uterine anomalies (CUAs) and placenta accreta spectrum (PAS), and to explore obstetric outcomes following hysteroscopic septal resection.Methods This retrospective cohort study included singleton pregnancies delivered at ≥22 weeks of gestation at a tertiary referral center between 2013 and 2024. PAS was diagnosed based on the 2019 International Federation of Gynecology and Obstetrics (FIGO) clinical or pathological criteria. The association between CUAs and PAS was evaluated using Firth’s penalized logistic regression analysis. Sensitivity analyses were additionally performed using conventional logistic regression models. Obstetric outcomes following hysteroscopic septal resection were descriptively analyzed.Results Among 2,891 pregnancies, 31 (1.1%) involved CUAs, including 11 pregnancies following hysteroscopic septal resection. PAS occurred more frequently in the CUA group than in the non-CUA group (9.7% vs. 1.3%, p < 0.01). Firth’s penalized logistic regression showed that CUAs were significantly associated with PAS (crude odds ratio [OR], 9.25; 95% confidence interval [CI], 2.42–26.1; p < 0.01). After adjustment for placenta previa or low-lying placenta, the association became stronger (adjusted OR, 21.8; 95% CI, 5.47–67.0; p < 0.001). Sensitivity analyses adjusting for advanced maternal age, assisted reproductive technology, and previous cesarean delivery showed consistent results. Cesarean delivery was significantly more common in pregnancies complicated by CUAs. In an exploratory descriptive analysis, no PAS cases were observed among following septal resection.Conclusion CUAs may be a potential risk factor for PAS. In contrast, our exploratory analysis did not identify PAS cases following hysteroscopic septal resection. Large-scale multicenter studies using PAS defined according to the diagnostic criteria proposed by FIGO are essential to validate these findings and clarify the underlying mechanisms.