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Table 2 : Descriptive summary of studies utilising Magnetocardiogram for NIEA analysis

From: A systematic review on the utility of non-invasive electrophysiological assessment in evaluating for intra uterine growth restriction

Year Paper Study population Gestational Age, Inclusion & Exclusion criteria Definition of IUGR Acquisition method Signal acquisition Signal processing
2003 Grimm et al. Case- control study 21–24 weeks. IUGR n = 30. Control n = 60. EFW < 5% and confirmed BW confirmed IUGR 31 channel SQUID biomagnetometer 2 min recordings sampling at 1 kHz. Band pass filters of 0.3 to 500 Hz. Smoothing with Savitzky-Goolay filter. Complex averaging carried out and maternal subtraction method applied a
2003 Anastasiadis et al. Case control study 34–37 weeks. IUGR (n = 11) Control (n = 19) AC,HC or BPD < 2SD below the average Single channel biomagnetometer 32 s duration each. Sampling frequency of 256 Hz. Power spectral analysis with Fast Fournier transform. Band pass filtered with cut off frequency of 0.1–100 Hz
2006 Schneider et al. Case control study 28–39 weeks. IUGR (n = 36) Control (n = 29) Exclusion criteria: known cardiac or fetal malformations, No definition of IUGR 31 channel SQUID biomagnetometer 5 min recording at a sampling rate of 1000 Hz Filtering band pass between 0.3 -500 Hz. QRS complexes averaged over 256 beats.
2006 Van Leeuwen et al. Case control study 15–42 weeks IUGR (n = 27), Control (n = 47). Singleton pregnancies. Arrythmia and CHD excluded EFW < 10% 230 FMCG recorded from normal foetuses. 29 FMCG recorded from IUGR group, Acquired using 61 or 37 channel biomagnetometer 5 min recordings Sampling at 1 kHz. Bandpass filters of 1-200 kHz Fetal beats identified on QRS template using 20–30 beats. PQRST averaged over 300 beats for CTI.
2011 Fukushima et al. (Power spectral analysis) Case control study 28–39 weeks. IUGR (n = 12) and controls (n = 35). EFW < 10% 64 channel SQUID biomagnetometer 5 min recordings. Maternal subtraction method utilised. Means were average over 300–500 beats. Power spectrum in frequency domain derived from maximum entropy method. LF domain 0.01–0.15 Hz. HF domain 0.15–0.4 Hz
2013 Sriram et al. Case control study 30–38 weeks. IUGR. Only heart rate data for sleep states were analysed EFW < 10% 151 sensor SQUID array system. N = 40 available for analysis. Pattern A was quiet sleep state and pattern B was active sleep state. Between 10 and 30 min. Sampling rate of 312.5 Hz Band pass filtered between 0.5 to 50 Hz.Hibert transform approach utilised to identify R waves. Parameters derived from 6 min windows
2016 Bolin et al. Case control study 33–37 weeks. IUGR (n = 21), hypertensive mothers (n = 46) and control (n = 74). No fetal cardiac pathology or arrythmias. EFW < 10% 151 sensor SQUID array system. CTI averaged over 1 min after maternal with maternal subtraction method Not described
  1. AC abdominal circumference, BPD bi parietal diameter, CTI cardiac time intervals, EFW estimated fetal weight, HC head circumference, IUGR intra uterine growth restriction, SD standard deviation. a. Schneider U et al. [67]