In a retrospective study it was possible to show that of 110 cases with operative delivery, performed due to suspicious or pathological fetal blood acidity findings, 93.6% were justified. A pre-pathological or pathological umbilical cord artery pH of < 7.25 was taken as the basis for correct clinical management ("true" positive cases). There was a clear relationship between the pH of the umbilical artery blood and the clinical state of depression in the newborn. This study shows that, with the help of combined fetal supervision using cardiotocography (CTG) as a screening method and fetal blood analysis (FBA) as a method of differentiation, early stages of threatened fetal acidosis can be reliably detected without having too high a rate of operative deliveries, which must inevitably result when continuous CTG supervision is used on its own. Obstetricians should therefore try to prevent severe acidosis combined with a corresponding clinical state of depression of the newborn. This requires the use of modern monitoring (CTG and FBA) and prompt clinical measures (tocolysis or termination of labor) when the pH levels are reduced or are apparently falling.