Perinatal clinicians are confronted with the problem that they are supposed to gather information about the condition of the unborn child almost exclusively by monitoring the rate of the fetal heart. Human heart rate recording, however, is no more or less informative in utero than in the newborn nursery. Determination of the pre-ejection period (PEP) of the fetal heart might provide information regarding the performance of the heart of the human fetus in utero and about its cardiovascular adjustments during fetal distress. On the verge of introduction of clinical human fetal PEP monitoring, this article presents a review of the results obtained from chronically instrumented fetal animals as well as some preliminary data from human perinatal research. Finally, possible future developments in human fetal PEP recording are anticipated and it is concluded that the most promising feature of the PEP for clinical use appears to be its predictive value as an early antepartum indicator of possible fetal distress during subsequent labor.