Maternal and Neonatal Implications of Subchorionic Hematoma Detected on Ultrasound: A Systematic Review, Meta-Analysis, and Case-Based Imaging Analysis of Real-World Pregnancies

Objective: To systematically evaluate maternal and neonatal outcomes associated with subchorionic hematoma (SCH) detected on ultrasound in pregnancy, integrating evidence from real-world cohorts and meta-analytic synthesis. Methods: Following PRISMA 2020 guidelines, MEDLINE, Embase, PubMed, Scopus, and Cochrane Library were searched (January 2000–July 2025). Eligible studies included prospective or retrospective cohorts, case–control studies, and randomized datasets reporting maternal or neonatal outcomes in pregnancies complicated by SCH. Data extraction targeted miscarriage, stillbirth, preterm birth, placental abruption, hypertensive disorders of pregnancy (HDP), and intrauterine growth restriction (IUGR). Pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using random-effects models. Study quality was assessed via the Newcastle–Ottawa Scale (NOS). Results: Across 24 studies encompassing >92,000 pregnancies, SCH was associated with significantly increased risk of miscarriage (OR 2.14, 95% CI 1.88–2.43; I² = 12%), stillbirth (OR 1.72, 95% CI 1.21–2.45; I² = 26%), preterm birth (OR 1.65, 95% CI 1.33–2.04; I² = 28%), and placental abruption (OR 2.30, 95% CI 1.74–3.05; I² = 20%). Associations with HDP (OR 1.31, 95% CI 0.97–1.77) and IUGR (OR 1.29, 95% CI 0.91–1.82) were nonsignificant but trended toward increased risk. Funnel plots revealed minimal publication bias. Subgroup analysis suggested stronger associations when SCH was diagnosed in the first trimester and when hematoma size exceeded 50% of the gestational sac. Conclusions: SCH is a clinically significant ultrasound finding that confers increased risks of miscarriage, preterm birth, stillbirth, and placental abruption. Risk stratification should incorporate hematoma size and timing. While associations with hypertensive disorders and IUGR remain inconclusive, heightened antenatal surveillance is warranted. Future studies should address standardized reporting of SCH dimensions and its integration into risk prediction models.