[Study of a new fetal blood gas parameter: oxygen saturation].

The oxygen saturation, together with the other parameters of the acid-base balance, was studied in the umbilical vessels of 60 neonates born by vaginal delivery. These assays were used to define the normal range, which is 28 to 38% in the umbilical artery and 62 to 74% in the umbilical vein. The umbilical arterio-venous gradient was always negative. Correlations with the pH and the serum lactate concentration demonstrate that oxygen saturation is a good parameter for the evaluation of foetal hypoxia, which has the advantage of being easily measurable.