(Am J Obstet Gynecol. 2015;213(3):259–261)
In newborns, acidemia can be common, but if it is caused by hypoxia with anaerobic metabolism, it can signal future morbidities. Since it was first proposed in the 1950s, base excess in umbilical cord blood at birth has been used to measure nonrespiratory acid-base status in infants. As most base excess scores are negative at birth, the phrase base deficit can be used synonymously. The reasoning behind considering this measure in relation to pH levels is to differentiate respiratory and metabolic acidemia.