The development and validation of an algorithm for real-time computerised fetal heart rate monitoring in labour

Objective To develop and validate a computerised algorithm for the interpre tation of the characteristics of fetal heart rate monitoring in labour. Design Prospective observational study. Setting Labour ward in a tertiary hospital. Sample Intrapartum cardiotocograms from 24 pregnancies. Methods A computerised algorithm was developed to assess the fetal heart ba seline rate, variability, the number of accelerations and the number of dec elerations. Twenty five minute segments of cardiotocograms were interpreted by the algorithm and also by seven expert reviewers independently. The rev iewers were unaware of the outcome of labour. The reliability of the charac teristics of cardiotocography and the validity of the computerised algorith m were assessed using the intraclass correlation coefficient and weighted k appa statistic for continuous and ordinal variables respectively. Results The inter rater reliability of the baseline fetal heart rate and th e number and type of decelerations was good (intraclass correlation coeffic ient 0.93, 0.93 and 0.79, respectively). The reliability of baseline variab ility (kappa = 0.27) and accelerations (intraclass correlation coefficient = 0.27) was poor. The computerised algorithm had good agreement with the re viewers for the baseline fetal heart rate (intraclass correlation coefficie nt 0.91 to 0.98) and the number of decelerations (intraclass correlation co efficient 0.82 to 0.91), but was less valid as regards the number of late d ecelerations (intraclass correlation coefficient 0.68 to 0.85) and the numb er of accelerations (intraclass correlation coefficient 0.06 to 0.80), and was invalid as regards baseline variability (kappa 0.00 to 0.34). Conclusions The high level of validity of the computerised algorithm for th e estimation of the baseline fetal heart rate and the number of deceleratio ns justifies its further technical development.