Influence of the maternal ECG on the abdominal fetal ECG complex.

Abstract Applying averaging techniques to the abdominal fetal electrocardiogram, the possibility exists that some peaks are wrongly considered to be part of the averaged fetal PQRST complex when the disturbance from the maternal ECG is not completely eliminated. A method that makes use of laboratory averaging equipment is described with which all the disturbances, originating from the maternal ECG, in the averaged fetal ECG complex are suppressed. It is shown that it is wise to average only those fetal ECG complexes in which the R waves do not coincide with the maternal QRS complex. With the described procedure a considerable improvement in the representation of the averaged fetal PQRST complex from abdominal leads is reached. The method is demonstrated with 4 abdominal fetal electrocardiograms.