Recurrent Pregnancy Loss and Adverse Outcomes in Chronic Intervillositis of Unknown Etiology: A Systematic Review and Meta‐Analysis

ABSTRACT Aim To evaluate the reproductive outcomes associated with chronic intervillositis of unknown etiology (CIUE) and to clarify its clinical relevance in women presenting with recurrent pregnancy loss (RPL). Methods A systematic review and meta‐analysis were conducted across PubMed, Embase, Cochrane Library, and OVID databases through September 2025. Studies reporting histologically confirmed CIUE with documented RPL outcomes were included. Pooled prevalence estimates were calculated using generalized linear mixed models within random‐effects frameworks to account for between‐study variability. Results Six studies encompassing up to 263 pregnancies were analyzed. The pooled prevalence of RPL was 37.3%, while live birth, CIUE recurrence, intrauterine growth restriction, and perinatal death were 52.6%, 39.6%, 64.1%, and 13.7%, respectively. Maternal autoimmune disease and fetal chromosomal abnormalities were relatively uncommon. Despite substantial heterogeneity, the overall pattern indicated a consistent burden of adverse pregnancy outcomes in affected women. Conclusions CIUE is closely associated with pregnancy loss, fetal growth restriction, and perinatal death and is characterized by a high recurrence rate of approximately 40% in subsequent pregnancies, underscoring its clinical importance in women with unexplained RPL. Early pathological recognition and individualized surveillance may improve pregnancy management and counseling. Further multicenter prospective studies are warranted to define optimal diagnostic and therapeutic strategies.