A new method of assessing fetal heart rates with potential for analytical quantification

We devised a method using a matrix to condense the large scale of fetal heart rates (FHR) without altering their characteristics. This matrix was arranged by FHRs at one beat per minute (bpm) intervals in rows, beat-to-beat differences (DFHRs) at one bpm intervals in columns and probabilities in the corresponding elements, respectively. Three matrices were calculated for Groups I, II and III: from 22 fetuses at 18-24 weeks, from 27 at 28-32 weeks and from 66 at 37-41 weeks of gestation, respectively. It was evident that the FHRs within the cumulative probability of 0.98 moved at 138-170 bpm in Group I, through 126-170 bpm in Group II onto 124-170 bpm in Group III. DFHRs spread symmetrically around zero bpm of DFHR for the entire scope of FHR values, irrespective of the age of gestation. This method can also be used for assimilating FHR data for analytical quantitation.