Monitoring fetal development with magnetocardiography

Fetal heart rate variability (fHRV) is useful for noninvasive assessment of the status of the autonomic nervous system of the developing fetus. In this pilot study we acquired fetal magnetocardiograms (fMCG) in a magnetically shielded environment. Each recording was of 5-minute duration and was subsequently repeated in a high-frequency noise environment to examine the feasibility of conducting future recordings in clinical environments that lack facilities for magnetic shielding. The fMCG (n=17) were recorded at 9 spatial locations above the pregnant abdomen at 26 to 35 weeks gestational age (GA) by a second-order SQUID gradiometer. The signal-to-noise was adequate for reliable QRS detection even in the noisy environment, especially for GA >/= 30. The total spectral power of the RR-series, as well as band powers at low (0.05 to 0.25 Hz) and high (0.25 to 1.00 Hz) frequencies independently exhibited an increasing trend with GA. There was no evidence of bias in spectral power due to lack of shielding. These results provide experimental evidence supporting further studies in magnetically unshielded environments and may have an important implication for future clinical use of fMCG in the assessment of fHRV.