Observations on fetal behavioral states at term in normal pregnancy

Abstract

The authors report on results of examinations of 18 women between the 38th and 42nd weeks of pregnancy in respect of the observation of foetal sleep/waking cycles. The following parameters were noted simultaneously, i.e. with time synchronicity: foetal heart rate, foetal eye movements, foetal thorax movements, and movements of the body and extremities. On the basis of the criteria published by Prechtl (1974) and by Nijhuis et al. (1982) it is possible to define with relative accuracy foetal sleep/waking cycles just before the term of birth; 4 independent researchers achieved agreement in the allocation of the various cycles in 86% of the cases investigated by them. In view of the fact that monitoring is complicated and exacting, recording cannot be continuous all the time and certain dropout periods must be taken into account. This applies, for example, to the foetal heart rate, foetal eye movements and movements of the thorax. The average dropout time during recording of foetal heart rate is 16%, during recording of foetal eye movements 22%, and of foetal thorax movements 3%. 11% of the recordings could not be evaluated because of poor recording quality and faulty monitoring. In the study under reference the shortest period of a cycle was three minutes, whereas the longest phase recorded so far was 39 minutes. In 55% of all monitored pregnancies between the 38th and 42nd weeks of pregnancy the foetus was awake, whereas in 45% the foetus was found to be asleep.