Application of Quantitative Hemorrhage Detection in Fetomaternal Hemorrhage Syndrome for the Diagnosis of Hemolytic Disease of the Newborn

Inclusion Criteria: * Gestational Age: Singleton pregnant women with gestational age ≥ 20 weeks. * Clinical High-Risk Factors (meeting at least one of the following criteria): * Traumatic Factors: Abdominal trauma (e.g., traffic accident, fall), intrauterine fetal version, amniocentesis, chorionic villus sampling (CVS). * Obstetric Complications: Placental abruption, placenta previa, preeclampsia, unexplained antenatal hemorrhage, post-interventional therapy for twin-twin transfusion syndrome (TTTS). * Fetal Abnormalities: Fetal growth restriction (FGR), unexplained abnormal fetal heart rate monitoring, fetal hydrops, fetal anemia (elevated middle cerebral artery peak systolic velocity (MCA-PSV) detected by Doppler ultrasound). * High-Risk Population with Maternal-Fetal Blood Group Incompatibility: Maternal-fetal ABO or Rh-negative blood group incompatibility; positive result of the first-trimester antenatal antibody screening in pregnant women. Exclusion Criteria: * Pregnant women complicated with severe hematological diseases (e.g., coagulation disorders, immune thrombocytopenic purpura) or autoimmune diseases. * Newborns who withdrew treatment for non-study-related reasons or were lost to follow-up after birth, resulting in missing outcome data. * Termination of pregnancy due to various causes. * Failure to complete the analysis due to unqualified core clinical data (e.g., quantitative hemorrhage test results, bilirubin levels) or unsatisfactory specimens (hemolysis, insufficient volume).