Neonatal metabolic acidosis at birth: In search of a reliable marker

Abstract Objective A newborn may present acidemia on the umbilical artery blood which can result from respiratory acidosis or metabolic acidosis or be of mixed origin. Currently, in the absence of a satisfactory definition, the challenge is to determine the most accurate marker for metabolic acidosis, which can be deleterious for the neonate. Methods We reviewed the methodological and physiological aspects of the perinatal literature to search for the best marker of NMA. Results Base deficit and pH have been criticized as the standard criteria to predict outcome. The proposed threshold of pathogenicity is not based on convincing studies. The algorithms of various blood gas analyzers differ and do not take into account the specific neonatal acid–base profile. Conclusion Birth-related neonatal eucapnic pH is described as the most pertinent marker of NMA at birth. The various means of calculating this value and the level below which it seems to play a possible pathogenic role are presented.