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 |