Processing the Abdominal Fetal ECG

A system capable of recording fetal electrocardiograms and fetal vectorcardiograms is described. This system has enabled us to record signals of higher quality than any that have been published to date. It is also possible to study some of the diagnostic potentials of the fetal electrocardiogram signal during the course of gestation. Records with this system have been obtained during the period of 20 weeks to 40 weeks gestation using active surface electrodes placed on the mother´s abdomen. The system has the following features: 1. low noise recording of the fetal signal; 2. signal averaging to improve signal to noise ratio; 3. removal of the maternal electrocardiogram component; 4. coordinate axis rotation for the display of the fetal vectorcardiogram and/or electrocardiogram in any convenient frame of reference. This system is currently being used to study the characteristics of the human fetal electrocardiogram in vivo.