Umbilical Cord Arterial Blood Gas Parameters as Predictors of Hypoxic-Ischemic Encephalopathy Severity in Neonates with Low Apgar Scores

Abstract

Background: Hypoxic-ischemic encephalopathy (HIE) severity following perinatal asphyxia is graded by clinical criteria (Sarnat stages I–III) and strongly influences outcomes. Umbilical arterial blood gases, including pH and base deficit (BD), reflect the degree of fetal acidemia from intrapartum hypoxia. Objectives: To evaluate whether umbilical arterial pH and BD at birth predict the subsequent HIE in term neonates with 5-minute Apgar scores ≤5. Methods: In this prospective observational cohort of term neonates (gestational age ≥37 weeks) with 5-minute Apgar ≤5, umbilical arterial pH and BD were recorded at birth (double-clamped cord samples). Neonates were classified by Sarnat criteria. Mean pH and BD across HIE groups were compared (ANOVA), and correlations with HIE stage were assessed (Spearman’s ρ). Results: Eighty infants met inclusion criteria. HIE classification was: None (n=40), Stage I (n=20), Stage II (n=17), Stage III (n=13). Mean umbilical arterial pH progressively decreased with increasing HIE severity; mean BD increased (both ANOVA p<0.001). pH and BD showed strong monotonic relationships with HIE stage (Spearman’s ρ = –0.94 and +0.80, respectively; both p<0.001). Conclusion: In term neonates with low 5-minute Apgar scores, lower cord arterial pH and higher BD were strongly associated with more severe HIE, supporting the clinical value of cord blood gas analysis for early risk stratification.