Can Fetal Heart Rate Monitoring ultimately become a useful tool in Obstetrical Practice?

Abstract

Currently, fetal heart rate (FHR) monitoring is the most widely used method for antepartum and intrapartum fetal surveillance. Antenatally, the introduction of FHR monitoring has been associated with a parallel decrease in perinatal mortality. However, a number of small scale controlled studies has failed to demonstrate the usefulness of FHR monitoring, both antenatally and intrapartum. Several possible explanations could be responsible for this apparent incongruous observation. Although FHR is normally easy to record, the quality of tracing is often sub-optimal, and adds to the complete lack of uniform interpretation shown in studies comparing interobserver and intra-observer variations. In addition, there is now an abundance of human observations and animal studies demonstrating that gestational age, in addition to the development of fetal behavioural status, are the most important factors that will alter FHR patterns under normal conditions and in response to hypoxaemia. It is also becoming evident that growth-restricted fetuses have inherent differences in FHR patterns when compared to normally-grown fetuses, possibly due to a delay in the maturation of the autonomic control of the fetal heart in response to chronic hypoxaemia. Therefore, in order to use electronic FHR monitoring, it is becoming necessary for the clinician to start learning about the physiology of the fetus, its changing evolution with advancing gestation, and the various ways these are represented in FHR tracings under stress or distress. With the development of computerized FHR analysis that virtually eliminates interobserver and intra-observer variation in interpretation, in addition to the knowkdge of the factors influencing FHR, it is now possible and timely to conduct a properly designed, large scale, randomized clinical trial to demonstrate whether or not both antenatal and intrapartum FHR monitoring can ultimately become useful tools in obstetrical practice.