The proposed system is based on a high-resolution electrocardiograph in which the electrodes are positioned on maternal abdomen. The acquired signals are processed using a completely unsupervised software for fetal ECG extraction based on independent component analysis, maternal ECG canceling and a quality index optimization. The electrocardiograph is constituted by a light-weight and light-dimension portable unit, which acquires the signals and transmit them to a computer where the analysis software runs. The software can also extract heart rate variability features, which provide information about fetal autonomic nervous system maturation. The system allows to accurately extract fetal ECG since the second trimester of pregnancy even in critical conditions like noise presence and uterine contractions.
The system is innovative since relays on a novel method for fetal ECG extraction that is based on the optimization of a quality index of fetal ECG designed considering the pseudo-periodicity of the signal. Such method is integrated with more traditional approaches for fetal ECG extraction: maternal cancelling and independent component analysis. Moreover, the method does not relay on preliminary assumptions regarding QRS complex periodicity and shape, thus it is able to detect also aberrant QRS complexes or arrythmias. The procedure, completely unsupervised, can be applied both in clinics and for self-monitoring of fetal health during pregnancy. Heart rate variability features extraction, both in time and frequency domain, allows the characterization of fetal autonomic nervous system maturation. The gold-standard for this type of assessment is magnetocardiography, which has a high cost and is not mobile.