Evaluation of Soluble FMS-like Tyrosine Kinase-1 as a Biomarker in First Trimester Missed Miscarriage

Background: Missed miscarriage is one of the common complications of pregnancy and often occurs without clear clinical signs. Soluble FMS-like tyrosine kinase-1 (sFlt-1), an anti-angiogenic marker, may help to identify missed miscarriage through its altered serum levels in pregnant women.Objective: To determine serum sFlt-1in pregnant women with missed miscarriage, assess its potential role as a predictive biomarker for first trimester missed miscarriage, and compare its diagnostic performance with beta-human chorionic gonadotropin (β-hCG).Materials and Methods: This case-control study was conducted at Azadi Teaching Hospital over 8 months from 1 February to 1 October 2025. The case group consisted of 45 pregnant women with missed miscarriage, while the control group included 45 pregnant women with singleton viable pregnancies. The gestational age of all participants was ≤ 12 weeks. Serum sFlt-1 and β-hCG levels were measured for all participants.Results: The mean sFlt-1 level was significantly lower in the case group than in the control group (5.55 ± 0.46 ng/mL vs. 8.5 ± 3.1 ng/mL, P-value of 0.0001). A serum sFlt-1 level of < 6.58 ng/mL achieved 100% sensitivity and 97.8% specificity. A significant positive correlation was observed between serum sFlt-1 and β-hCG levels. Except for β-hCG, the evaluated demographic and obstetric variables were not significantly correlated with sFlt-1 levels (P-value > 0.05).Conclusion: Serum sFlt-1 and β-hCG levels were markedly reduced in first trimester missed miscarriage, supporting their potential role as biomarkers of pregnancy viability. Both markers demonstrated a moderate positive correlation, suggesting shared physiological pathways. These findings suggest potential clinical utility in early pregnancy assessment, but further validation is required.