Fetal heart monitoring by SQUID magnetometry

The author has successfully carried out fetal magnetocardiographic studies using a Superconducting Quantum Interference Device (SQUID) magnetometer. The technique, which is completely non-invasive and does not even require physical contact with the subject, is based on the detection of the magnetic fields generated by cardiac activity. Because magnetic fields are unaffected by changes in the electrical conductivity of the medium, measurement of the fetal magnetocardiogram (FMCG) may well prove not only simpler but more useful than the fetal electrocardiogram (FECG). The FMCG has been studied in a small group of normal subjects with the gestational age ranging from 28 to 35 weeks. In contrast to the FECG, the measured signal is completely uncontaminated by the maternal signal. The QRS complex is clearly visible in all cases and can be used for accurate beat-to-beat interval measurement. Further details of the fetal heart waveform, including the P-wave, can also be obtained by signal averaging