It is the aim of obstetric medicine to achieve optimum safety for both mother and child with a minimum of surgery. In normal clinical routine, this demand cannot be fully met by the sole use of cardiotocography for monitoring the foetus sub partu. Obviously the weak point of cardiotocographical diagnosis is that often there is no imminent or beginning hypoxia or acidosis of the foetus associated with suspicious or pathological heartbeat patterns. This results in a large number of unnecessary deliveries by Caesarian section, or complicated vaginal surgery. We must draw the conclusion from this that cardiotocography is merely a-selective method. It is imperative to apply additionally a biochemical method for properly diagnosing foetal hypoxia or acidosis. The author also comments on accusations made by K. Hammacher in a preceding publication.