A Study of Cord Blood Bilirubin as A Predictor of Neonatal Hyperbilirubinemia of All Term Newborns of O-Positive and All Rh-Negative Mothers at A Tertiary Care Hospital

Background: Neonatal hyperbilirubinemia is one of the most common clinical conditions in the early neonatal period, affecting a large  proportion of term newborns.Neonates born to O-positive and Rh-negative mothers are at increased risk due to immune-mediated hemolysis (ABO/Rh incompatibility).Therefore, this study was undertaken to evaluate the role of cord blood bilirubin as an early predictor of neonatal hyperbilirubinemia and to determine an optimal cut-off value for clinical use.

Methods: This study was a prospective, hospital-based observational study conducted in the Neonatal Intensive Care Unit and Department of Paediatrics of a tertiary care hospital over a period of 12 months. 173 term neonates born to O positive or Rh-negative mothers were included.Data on demographic, clinical, maternal, and laboratory parameters were systematically collected.Correlation analysis between cord blood bilirubin and postnatal bilirubin,ROC curve used to determine optimal cut-off value,diagnostic accuracy assessed using sensitivity, specificity, PPV, and NPV .

Results: Among 173 term neonates, 46.2% developed significant hyperbilirubinemia requiring treatment. Mean cord blood bilirubin was 1.71 ± 0.44 mg/dL and was significantly higher in treated neonates (p < 0.001). A cut-off of 2.1 mg/dL showed 100% specificity and PPV, with low sensitivity (32.5%). Hyperbilirubinemia was more common in ABO/Rh incompatibility and DAT-positive cases. Cord bilirubin showed a moderate positive correlation with 48-hour serum bilirubin (r = 0.354, p < 0.001), indicating its utility as an early predictor.

Conclusion: Cord blood bilirubin is a simple and reliable early predictor of neonatal hyperbilirubinemia with high specificity. Although its sensitivity is limited, it is particularly useful in identifying high-risk neonates, especially in cases of ABO/Rh incompatibility. It should be used alongside clinical assessment and follow-up for optimal management.