The authors evaluated a total of 1,237 cardiotocograms obtained from 138 pregnancies where premature delivery was imminent, 49 pregnancies with intrauterine retardation and 10 pregnancies without pathological findings from a clinical and anamnestic point of view. The cardiotocograms resulted from antepartal screening, and the Fischer score was used for evaluation. Restricted fetal respiration was assumed in all cases where prepathological CTGs were significantly more frequent in the course of pregnancy (24%) and where there was a significant increase in such findings immediately before delivery (41%) in the event of imminent premature birth, compared with normal controls (10%) and pregnancies with intrauterine retardation in the absence of premature uterine contractions (13%). Similar findings were also obtained for individual parameters of the fetal heart frequency such as the oscillation frequency, oscillation amplitude, acceleration and deceleration. By way of comparison with normal controls of the same age it is insured in each case that the disturbance observed expresses a respiratory insufficiency in the feto-placento-maternal unit rather than an immature fetal heart and circulatory system. In this connection, particular hazards exist during early gestation where a premature delivery is imminent, whereas IUR carries only a limited risk. This assumption is reinforced by the greater number of prepathological findings encountered in pregnancies which have successfully been prolonged (beyond the 37th week), compared with normal controls of the same age. The connections shown between a prepathological CTG (particularly in the last week before delivery) and a greater frequency of intra- and postnatal disturbances (hypoxia, acidosis morbidity, impaired adaptation) confirm the value which must be attached to a prepathological cardiotocographic finding. In this connection it is important to include results gained in the course of monitoring and to see if the antepartal CTG is normal at all times, prepathological at all times or, in the case of variations, normal or prepathological in the end.