[Acid-base equilibrium in healthy newborns. Pattern of normality in Mexico City].

During their spontaneous recovery after birth, the acid-base balance was studied in 32 healthy newborns. The observation period lasted for 4 hours. Determinations were carried out, both in umbilical vessels as in central arterial blood. The most outstanding phenomenon was an increase in acidosis at 30 minutes of life. The metabolic component predominating over the respiratory was a definitely evident fact. At the end of four hours, the acid-base balance reached figures considered normal for the adult.