Background: Umbilical cord pH is commonly used to assess the risk of poor neurological outcomes in high-risk newborns. Although severe acidemia in neonates has been strongly linked to birth asphyxia and long-term complications, the implications of mild to moderate acidemia remain uncertain.

Aim:This study aimed to investigate short-term outcomes of late preterm and term infants born with mild-to-moderate cord blood acidosis and to compare the predictive ability of pH and base excess.

Methods: This was a retrospective cohort study, including term and late preterm (≥34 weeks) neonates with mild–moderate umbilical cord blood acidosis, defined as pH 7.0–7.2 or base excess between −12 and −16. Data including demographic, clinical, and laboratory measures were extracted. The cohort population was stratified based on the level of acidosis, mild or moderate, with separate analyses performed by definitions of pH and BE. Mild acidosis was defined as cord blood pH 7.13–7.20 and base excess > −12 and moderate acidosis was defined as cord blood pH 7.00–7.12 or base excess between −12 and −16.

Results: The study included 337 newborns. Most had mild acidosis, but 90 infants had BE of −12 to −16 and 86 infants had pH 7.00–7.12. Rate of NICU admission was 12.8% (43/337), rising up to 27% among newborns with moderate acidosis. The leading cause for admission was respiratory distress, and there were no cases of moderate–severe HIE. Renal and hepatic dysfunction were more common in moderate compared to mild acidosis; however, most lab abnormalities were mild and transient. Using ROC curves, BE ≤ −12 was found to be a better predictor for renal and liver involvement than pH ≤ 7.12.

Conclusion: Moderate acidosis in cord blood was associated with an increased incidence of short-term neonatal morbidities, NICU admissions and renal or liver dysfunction compared to mild cord blood acidemia. BE correlated with abnormal values better than pH. Infants with cord gas BE levels ≤ −12 may benefit from closer clinical monitoring and assessment of renal and liver function.

Keywords:
umbilical cord blood, acidosis, base excess,pH