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Table 1 : Descriptive summary of studies utilising non-invasive fetal electrocardiogram 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 Inclusion criteria Definition of IUGR Acquisition method Signal acquisition Signal processing
1981 Karinemi et al. Case control study N = 65 from normal pregnancies with no fetal acidosis at birth. n = 68 with IUGR. n = 84 with post dates pregnancies BPD < 5% NIFECG using HP 8030A Cardiotocograph Recorded manually on magnetic tape and digitalized at a 1000 samples per second)a R-R intervals detected no description provided)a. DI sampled over 5 min. Upper rejection limit of 5 bpm was utilised
1982 Brambati et al. Case control study N = 26 of fetuses suspected to be small for dates Small for dates by ultrasound or clinical exam (no explanation given) BW < 10% postnatally. NIFECG- system not specified N/A MECG subtraction method utilised. Signal delayed by 180 ms and 50 complexes averaged
1986 Pardi et al. Prospective cohort study 25 to 41 weeks of gestation. n = 68. Fetuses with malformations excluded AC < 5% NIFECG- system not specified N/A MECG subtraction method utilised. Signal delayed by 180 ms and 50 complexes averaged
2012 Graatsma et al. Prospective cohort study 20–42 weeks of gestation. Control (n = 90),IUGR (n = 30) EFW ≤10% and BW ≤10% corrected for GA NIFECG. Monica AN24. 5 electrodes utilised Recorded with a sample frequency of 1000 Hz. Duration = 7 h In depth analysis available from Pieri et al.b MECG subtraction method utilised. 50 FECG complexes averaged
2015 Stampalija et al. Case control study 26–34 weeks. IUGR n = 22, Control n = 37. Singleton pregnancies AC < 5% NIFECG. Monica healthcare. 5 electrodes utilised transabdominally 40 min recording. Sample frequency of 900 Hz MECG subtraction method as filter. FECG complexes averaged over a 2 s window.
PRSA applied to entire trace
STV measured using Dawes Redman criteria
2016 Stampalija et al. Case control study 25–40 weeks. IUGR (n = 66). Control (n = 79) Singleton pregnancies AC < 5% NIFECG. Monica healthcare. 5 electrodes utilised transabdominally 37 min. R-R wave pulse intervals were calculated with an accuracy of 1 ms. MECG subtraction method as filter. FECG complexes averaged over a 2 s window.
PRSA applied to entire trace
2016 Fuchs et al. Prospective case control study 28–42 weeks. IUGR = 93, IUGR with brain sparing = 37 and 324 healthy pregnancies EFW < 5% and only asymmetrical IUGR considered. BW was < 10% and ponderal index < 10% at birth NIFECG. KOMPOREL system. 6 electrodes on maternal abdomen, 30 min recording. No further information provided No information provided
2016 Fuchs et al. Prospective case control study 28–40 weeks. IUGR with normal CPR (n = 110), IUGR with decreased CPR (n = 29) and normal pregnancies (n = 549) EFW < 5% and only asymmetrical IUGR considered. BW was < 10% and ponderal index < 10% at birth NIFECG. KOMPOREL system. 6 electrodes on maternal abdomen, 30 min recording. No further information provided No information provided
2017 Velayo et al. Human- case control study 20–34 weeks IUGR n = 15, Control n = 20. Singleton pregnancies EFW and AC < 10% NIFECG 14 electrodes transabdominally 20 min recordings Bipolar recording. Sampling every 1 ms at 1 kHz 1-100 Hz band pass filtering. FECG signal averaging carried out.
  1. AC abdominal circumference,BPD Bi parietal diameter, BW birth weight, CPR Cerebro placental ration, CTI cardiac time intervals, EFW estimated fetal weight, GA gestational age, FECG fetal electrocardiogram, HC head circumference, MECG maternal electrocardiogram, NIFECG non invasive fetal electrocardiogram, IUGR intra uterine growth restriction, PRSA phase rectified signal averaging, SD standard deviation, STV short term variability
  2. a.Yeh et al. [54].b. Pieri et al. [66]