200: Mild neonatal acidemia is associated with neonatal morbidity at term

Abstract

Neonatal acidemia is associated with neonatal morbidity. Umbilical artery pH of 7.0 or 7.1 is often used as a threshold for assessing risk of neonatal morbidity and mortality. However, the relevance of mild acidemia above this threshold has not been adequately assessed. This study was designed to determine the association of incremental increases in pH and neonatal morbidity among neonates with mild academia, defined as pH between 7.11 and 7.19. This is a secondary analysis of a prospective cohort study of 8580 women who were admitted for labor at ≥ 37 weeks gestation within a single institution from 2010 to 2015. Umbilical cord blood gas assessment was performed during the study time. A composite neonatal morbidity index was created including death, respiratory distress, mechanical ventilation, meconium aspiration syndrome, suspected sepsis, hypoxic-ischemic encephalopathy, therapeutic hypothermia and seizures. Neonates with mild acidosis were divided into those with umbilical artery pH 7.11-7.14 and those with pH 7.15-7.19. Multivariable logistic regression was used to estimate the association between lower pH and neonatal morbidity while adjusting for confounders. Of the 8,580 participants, 669 (7.8%) had mild acidosis. Lower umbilical artery pH (7.11-7.14) was associated with increased risk of composite neonatal morbidity when compared to pH 7.15-7.19 (aOR 2.53 [1.59,4.03]; Table 1). Among individual components, lower pH was associated with increased neonatal respiratory distress and treatment for suspected sepsis although respiratory distress was no longer significant after adjustment. These data demonstrate that term neonates with mild acidemia at birth are at increased risk for immediate morbidity. Long term risks of mild acidemia at birth will need to be assessed, and the utility of potential interventions that benefit infants with moderate and severe acidemia should be explored among this population.