The impact of in vitro fertilization and intrauterine surgery on the incidence of placenta accreta spectrum and placenta previa: a 15-year retrospective cohort study

Background: To compare the incidence of placenta accreta spectrum (PAS) and placenta previa among unassisted conceptions and those conceived via in vitro fertilization (IVF) using fresh or frozen embryo transfer, and to evaluate the influence of prior intrauterine surgery—particularly surgical correction of a T-shaped uterus—on these outcomes. Methods: This retrospective cohort study was conducted at a single tertiary center and included 31,905 pregnancies managed between 2008 and 2023. The exposures were mode of conception (unassisted, fresh embryo transfer, frozen embryo transfer) and history of intrauterine surgery, particularly T-shaped uterine correction. The primary outcomes were the incidence of PAS and placenta previa confirmed at delivery. Cesarean hysterectomy was assessed as a secondary outcome reflecting maternal morbidity. Results: PAS was identified in 4.2% of pregnancies conceived via frozen embryo transfer—significantly higher than fresh embryo transfer (0.2%) and unassisted conception (0.09%) (P < 0.001). Placenta previa followed a similar trend, observed in 7.3% of frozen embryo transfer pregnancies versus 0.7% with fresh transfer and 0.3% with unassisted conception (P < 0.001). Prior intrauterine surgery, especially T-shaped uterine correction, showed a strong association with PAS (P < 0.001). Among women with such a surgical history, 18.7% developed focal PAS and 10.5% had placenta accreta. In our clinic, hysteroscopic metroplasty is selectively performed for severe T-shaped anomalies with narrowed uterine cavities prior to IVF. This study is the first to demonstrate a significantly increased incidence of PAS in IVF pregnancies following correction of a T-shaped uterus. Cesarean hysterectomy was notably more common in pregnancies complicated by PAS, especially in the frozen embryo group. Conclusion: Frozen embryo transfer pregnancies showed a disproportionately high risk of abnormal placentation. Prior correction of a T-shaped uterus emerged as a novel and significant risk factor for PAS. These findings underscore the importance of tailored fertility strategies, cautious surgical interventions, and preconception counseling in at-risk patients. Trial registration: This study was retrospectively registered. Ethical approval was granted by the institutional ethics committee (Approval No: 2023 − 848). The study was conducted in accordance with the Declaration of Helsinki.