Predicting long-term neurodevelopmental outcomes in very preterm neonates by umbilical cord gas parameters

Background: The predictive value of acidemia at birth on long-term neurodevelopmental outcomes remains poorly understood, especially in preterm neonates. Objective: This study aimed to assess the relationship between the umbilical artery acid-base status and major neurodevelopmental disability at an age of between 5 and 8 years among children born very prematurely. Study Design: We performed a secondary analysis of the data from a follow-up study of a prospective cohort of 457 children aged between 23 weeks and 31 weeks and 6 days from 1996 to 2001. Arterial cord gas parameters that were <10th percentile in the original cohort of 457 neonates (ie, pH of <7.1, base deficit of <−8.6 mEq/L, and a partial pressure of CO₂ of >77 mm Hg) were considered abnormal. Sensitivity analyses considered alternative definitions for abnormal cord gases including a pH of <7.0 or base deficit of <−12 mEq/L. The primary outcome was a composite of major neurodevelopmental disability, including an intelligence quotient score of <70, cerebral palsy, blindness, deafness, abnormal balance, impaired cognition, dystonia, and seizure disorder. A logistic regression analysis was used to adjust for race and caregiver intelligence quotient score and, in an additional analysis, for gestational age. Results: A total of 259 of 261 maternal-infant dyads were evaluated at a mean child age of 6.8 years, with complete umbilical cord gas data for 228 of those. Infants with an abnormal pH and a base deficit (defined above) were over 4-fold more likely to have the composite disability and an intelligence quotient score of <70. These increased odds persisted after adjusting for age and caregiver intelligence quotient score, but when considering gestational age as well, none of the umbilical cord gas parameters significantly predicted the presence of the composite disability or an intelligence quotient score of <70. However, when using the stricter umbilical cord gas criteria (ie, pH of <7.0 and a base deficit of <−12 mEq/L), a base deficit of <−12 mEq/L was independently associated with both neurodevelopmental disability and an intelligence quotient score of <70. Conclusion: When defined more strictly, abnormal umbilical cord gases, specifically a base deficit of <−12 mEq/L, are associated with an increased risk for major long-term neurodevelopmental disability and an intelligence quotient score of <70 in children born very prematurely.