Discovery of Candidate Biomarkers for Unexplained Stillbirth: A Pilot Proteomic Study Comparing Live Birth and Stillbirth

This pilot study aimed to identify novel serum protein biomarkers distinguishing antepartum stillbirth from live birth cases using LC-MS-based proteomics. After obtaining ethical approval and the patient consent, serum from three stillbirth cases and three live birth controls was analyzed using liquid chromatography-mass spectrometry. Z-scores and t-tests identified significantly differentially expressed proteins (p < 0.05), with the top candidate proteins being evaluated against validated against clinical profiles of cases and controls. Of 3,076 detected proteins, 472 were unique to the stillbirth group, and 1,275 were unique to the control group. We identified 100 proteins that were significantly downregulated in stillbirth cases compared to controls, while 48 proteins were significantly upregulated. Subsequently, the top 14 proteins were evaluated in relation to the clinical complications of the subjects. Among these, Vacuolar protein sorting-associated protein 13D, immunoglobulin kappa variable 3–20, and Lysozyme C demonstrated markedly distinct expression patterns. These novel proteins reflect vascular and placental dysfunction, cellular stress, and immune dysregulation that may contribute to stillbirth pathogenesis, acting as a multi-marker diagnostic panel. This study identifies three promising protein biomarker candidates for stillbirth prediction, paving the way for validation in larger cohorts and clinical assay development.