Thyroglobulin antibodies and their role alongside thyroid-stimulating hormone in abnormally invasive placenta

Background: Abnormally Invasive Placenta (AIP), encompassing placenta accreta, increta, and percreta, results from excessive trophoblastic invasion beyond the decidual barrier. This pathological process is associated with disrupted angiogenesis, elevated vascular endothelial growth factors, and altered immune responses. While multiple biomarkers have been investigated for predicting AIP, their diagnostic accuracy remains controversial. Recent evidence suggests a potential role for thyroid function markers including Thyroid Stimulating Hormone (TSH) and thyroglobulin antibodies (TgAb) in modulating placental invasion and vascular remodeling. Objective: To investigate the relationship between maternal thyroid function specifically serum levels of TSH and TgAb and the incidence and severity of AIP in pregnant women. Methods: This prospective case-control study included 105 third-trimester pregnant women at Tikrit Teaching Hospital, Iraq (November 2024 to June 2025). Participants were divided into three equal groups (N=35 each): AIP group (confirmed intraoperatively and histologically), placenta previa totalis (PPT) group without invasion, and healthy controls. Exclusion criteria included thyroid disease, autoimmune disorders, and other confounding obstetric or medical conditions. Thyroid markers (TSH, T3, T4, TgAb, TPOAb) were assessed via electrochemiluminescence. Diagnostic accuracy was evaluated using ROC analysis. Obstetric and neonatal outcomes were compared across biomarker levels. Results: Women with AIP had significantly lower TSH and higher T4 levels compared to PPT and controls (p