A Comprehensive Systematic Review of The Relationship Between Serum Progesterone Levels and the Success of Maintaining Pregnancy in Threatened Miscarriage

Introduction: Threatened miscarriage is a common obstetric complication, and serum progesterone levels are frequently measured to assess pregnancy viability. However, the prognostic accuracy of a single progesterone measurement and the therapeutic efficacy of progesterone supplementation remain areas of clinical debate and heterogeneous evidence. Methods: This comprehensive systematic review synthesized evidence from 57 studies (including meta-analyses, randomized controlled trials, and observational studies) to evaluate the relationship between serum progesterone levels and pregnancy maintenance success in women with threatened miscarriage up to 20 weeks' gestation. Data extraction focused on study population, progesterone measurement methodology, defined pregnancy outcomes, statistical associations, identified thresholds, and confounding factors. Results: The analysis demonstrated a strong inverse relationship between serum progesterone and miscarriage risk. Diagnostic accuracy was high, with a synthesized Area Under the Curve (AUC) of 0.85 (95% CI 0.81–0.88) for predicting viability (Yi Gong et al., 2024). Threshold-dependent performance was evident; levels