Noninvasive Recording of True-to-Form Fetal ECG during the Third Trimester of Pregnancy

Figure 2

(a) Transabdominal record at the 39th week of pregnancy. The fetal ECG R wave is quite visible. (b) The software automatically identifies the maternal ECG R waves. (c) The system calculates the average of 30 maternal cardiac cycles. Then the computer extracts in real time the averaged signal from each identified maternal ECG heart event. (d) The “cleaned” abdominal signal, maternal waves are removed. (e) Using the same peak detection algorithm the fetal ECG R waves are identified. (f) After averaging 40 fetal heart events true-to-form fetal ECG is received. (g) It is very important to remove maternal waves, because otherwise the averaged fetal ECG cannot be assessed.