Computerised analysis of fetal behaviour.

Conventional analysis of fetal behaviour is laborious and time-consuming. For it to have a role in a clinical setting, practical and more objective methods are necessary. We describe a computerised fetal behavioural analysis programme.

Computerised analysis of behaviour in normal and growth-retarded fetuses.

Fetal behaviour [fetal heart rate (FHR) variation and movements (FA)] was studied in 27 normally grown fetuses and in 18 fetuses with intrauterine growth restriction (IUGR). FHR and FA were recorded using a single 1.5 MHz ultrasound transducer and analyzed by computer.

Computerised estimation of the baseline fetal heart rate in labour: the low frequency line.

Objective: To develop and evaluate a computerised algorithm for the estimation of the fetal heart rate baseline (low frequency line) during labour.

Design: Retrospective observational study.

Methods: Fetal heart rate signals were obtained from women in labour using the Nottingham fetal ECG monitor.

Computerized analysis of behavior in fetuses with congenital abnormalities.

An observational study was undertaken to evaluate a computerized fetal behavior program in a clinical setting. Behavior of normal fetuses was compared with that of fetuses with a variety of congenital abnormalities. Forty-three fetuses were studied at 28-36 weeks; 26 were normal (49 recordings) and 16 had congenital abnormalities (26 recordings; ten had structural abnormalities of the central nervous system, one had Down's syndrome and five had other abnormalities).

The development of a hybrid expert system for the interpretation of fetal acid-base status.

This article presents the development of an expert system for the interpretation of fetal scalp acid-base status. The system consists of logistic transformations, back-propagation neural networks and decision algorithms connected in series. It checks for out-of-range errors and the physiological coherence between measurements.

The effect of different sampling intervals on the measurement of intrapartum fetal heart rate variability.

Objective: To test the hypothesis that increasing the sampling interval affects the intrapartum fetal heart rate (FHR) variability measurement.

Methods: Fetal electrocardiograms were obtained from women in labor. Using the peak of the fetal R wave, the R-R interval and FHR were calculated on a beat-to-beat basis.

The potential impact of PR interval analysis of the fetal electrocardiogram (FECG) on intrapartum fetal monitoring.

A retrospective study was performed at the Queens Medical Centre, Nottingham, UK to evaluate the potential value of PR interval analysis of the FECG compared to conventional intrapartum assessment with fetal heart rate monitoring. Two-hundred sixty-five labours were selected for monitoring. Outcome was assessed by the number of fetal scalp blood samples (FBS) performed and the associated incidence of acidosis in the first stage of labour, the mode of delivery and whether or not this was expedited for fetal heart abnormality or an abnormal scalp pH.

Changes in the PR interval--fetal heart rate relationship of the electrocardiogram during fetal compromise in chronically instrumented sheep.

Objectives: The evaluation of the changes in the relationship of the PR interval and fetal heart rate during prolonged fetal compromise in sheep at levels of acidosis comparable to those seen during human fetal compromise and to see whether these changes are potentially of use in the detection of fetal distress.

Study Design: A retrospective analysis of continuous fetal electrocardiogram recordings during graded fetal hypoxemia in 20 chronically cannulated fetal sheep was performed. Baseline recordings during normoxemia were compared with recordings during hypoxemia by use of Fisher's exact test and the Student t test.

Improved intrapartum surveillance with PR interval analysis of the fetal electrocardiogram: a randomized trial showing a reduction in fetal blood sampling.

Objective: Our goal was to test the hypothesis that the addition of fetal electrocardiogram time-interval analysis to conventional electronic fetal monitoring would significantly reduce the number of cases requiring fetal scalp blood sampling without an increase in adverse outcome.

Study Design: A randomized prospective trial was performed in 214 women with high-risk labor.

Results: There was a significant reduction in the number of cases that had fetal blood sampling performed in the fetal electrocardiogram plus electronic fetal monitoring group (risk ratio for electronic fetal monitoring alone 3.

The prediction of fetal acidosis at birth by computerised analysis of intrapartum cardiotocography.

Objective: To assess the capability of a computer software interpretation program, using intrapartum fetal heart rate and intrauterine pressure as recorded in a cardiotocogram to predict fetal acidosis at birth.

Design And Subjects: A retrospective analysis of digitised fetal heart rate and uterine activity values obtained from 73 high risk women in labour.

Setting: Two university teaching hospitals.

Computerised fetal heart rate analysis in labour--effect of sampling rate.

Objective: To study the effect of sampling rate on the accuracy of fetal heart rate recording in labour.

Design: Prospective observational study.

Methods And Subjects: The fetal heart rate was obtained from 153 fetuses in labour.

Atrioventricular block during fetal heart rate decelerations.

Electrocardiograms (ECG) was examined in 15 fetuses during fetal heart rate decelerations in labour. Sinus bradycardia was demonstrated in six cases and in two cases inversion of the P wave was seen. In seven cases there was complete dissociation of the P wave from the QRS complex, indicating complete atrioventricular heart block.

A comparative study of the fetal electrocardiogram recorded by the STAN an Nottingham systems.

Objective: To compare the T:QRS ratio recorded by the STAN and Nottingham fetal electrocardiogram (FECG) monitors.

Design: Prospective observational study.

Setting: London teaching hospital delivery suite and research unit.

Cumulative changes in the fetal electrocardiogram and biochemical indices of fetal hypoxia.

Previous studies have shown that the relationship between P-R interval of the fetal electrocardiogram (FECG) and the fetal heart rate (FHR) varies according to the acid-base status of the fetus. In the normal fetus there is a negative correlation between these two parameters. However, as acidosis develops, the relationship becomes positive.

Customised antenatal growth charts.

Charts for fetal growth do not take physiological variables into account. We have therefore designed a computer-generated antenatal chart that can be easily "customised" for each individual pregnancy, taking the mother's characteristics and birthweights from previous pregnancies into consideration. The adjusted birthweight range expected at 40 weeks' gestation is combined with a standard, longitudinal ultrasound-derived curve for intrauterine weight gain.

Signal processing of the fetal electrocardiogram.

There has been considerable interest in recent years in the monitoring of the well-being of the fetus by the analysis of changes in morphology of the fetal electrocardiogram (FECG) signal. In this article, a brief review is first made of the use of the scalp electrode method to obtain an enhanced FECG complex. Subsequently, the problems in extracting the fetal signal from measurements taken from the abdomen of the mother are discussed.