Int. J. Gynaecol. Obstet., 1986,24: 341- 352 International Federation of Gynaecology & Obstetrics 347 POOR PROGNOSTIC VALUE OF THE BASAL FETAL HEART RATE AS OBSERVED DURING ANTENATAL MONITORING H.J. ODENDAAL and T.J.v.W. KOTZE Department of Obstetrics and Gynaecology, University of Stellenbosch and Tygerberg Hospital and the Institute ftir Riostatistics. South African Medical Research Council, Tygerberg (Republic of South Africa) (Received March 2nd. 1986) Accepted April 29th. 1986) Abstract O dendaal HJ, Kotze TJvW (Department of Obstetrics and Gynaecology, University of Stellenbosch and Ty gerberg Hospital and the Institute for Biostatistics, South African M edical Research Council, Ty gerberg, Republic of South Africa). Poor prognostic value of the basal fetal heart rate as observed during antenatal monitoring. Int J Gynaecol Obstet 24: 347-352,1986. The basal fetal heart rate, accelerations, decelerations and amplitude and frequency of variation were scored in positive stress tests of I46 and in suspicious recordings of 296 patients. Positive tests scored lower for accelerations, decelerations and amplitude and frequency of variation but not for the basal heart rate. W hen the outcome was poor, as characterized by low 5-min Apgar score and intrauterine growth retardation, it was reflected by all parameters of the fetal heart rate pattern except for the basal heart rate. Keywords: Heart rate; Fetal monitoring; Antenatal; Scoring system. Introduction Antenatal fetal heart rate monitoring is performed in many different ways. In Hammacher’s first publication the uterus was not stimulated but the different character- istics of the fetal heart rate pattern were care- 0020-7292/86/$03.50 0 1986 International Federation of Gynaecology & Obstetrics Published and Printed in Ireland fully examined [ 5 I. In the American literature the stress test was at first recommended [4,12] , but the pendulum has recently swung back in favor of the non-stress test in the large majority of patients [ 1 I. Interpretation of fetal heart rate patterns can, however, be difficult. Interest in an accurate interpretation was very much stimulated by the report of Keirse [ 141 in which an inter and intra observer difference was demonstrated. In order to establish a more accurate and constant way of reporting the results, different scoring systems have been developed [ 2,8,9,- 11 ,151. In essence the scoring systems were designed in a similar way to the Apgar score and different characteristics were scored in a very rigid manner where each characteristic carried exactly the same weight. It is question- able that the presence of accelerations, which disappear very early when the fetus is compromised, carries exactly the same weight as the basal heart rate which only changes terminally. In order to interpret fetal heart rate patterns more accurately, knowledge regarding the importance of each characteristic of the fetal heart rate pattern is mandatory. This study was therefore undertaken to study the influence of these characteristics of the fetal heart rate pattern on the fetal outcome. Patients and methods This study consists of a retrospective analysis of 146 positive and 296 suspicious