In vitro fertilization and the risk of placenta accreta spectrum: a systematic review and meta-analysis

Placenta accreta spectrum (PAS) is an increasingly common obstetric complication, characterised by the abnormal attachment of placental villous tissue to the uterine wall. Medline, Embase, Scopus, and Google Scholar were searched to identify observational studies that provided data on IVF pregnancies and PAS at birth between September 1980 and April 2025. The methodological quality of studies was assessed using the Newcastle-Ottawa Scale. Data were combined using a random-effects, generic inverse-variance approach, which allows the inclusion of diverse relative risk estimates in a single meta-analysis. The primary measures were the incidence of nulliparity, placenta previa, previous cesarean deliveries, and the type of IVF techniques used. The risk of both PAS and placenta previa was significantly increased in IVF compared to spontaneous conception (SC) pregnancies (p = 0.002 and p = 0.005, respectively), and the risk of PAS was significantly (p = 0.002) increased in patients undergoing frozen embryo transfer (FET) compared to those undergoing fresh embryo transfer. A significantly (p = 0.001) higher number of patients with IVF pregnancies were nulliparous compared to SC pregnancies. Due to the heterogeneity and poor quality of the included studies, the evidence that IVF is an independent factor in the development of PAS during pregnancy remains scant and limited. Any association between IVF and PAS is likely indirect, mediated through higher rates of placenta previa and prior uterine surgery, rather than a direct biological effect of IVF itself.