title: Comparison of fetal and maternal heart rate measures using electrocardiographic and cardiotocographic methods.
abstract: OBJECTIVE
  To determine the reliability at term of: (1) two methods of measuring fetal heart rate (HR), electrocardiographic (ECG, the 'gold standard') and cardiotocographic (CTG) and (2) two ECG methods of measuring maternal HR variability over relatively brief periods of time (s-min).
  
  
  METHODS
  During 20 min of rest (N=39) and during 2 min of auditory stimulation (mother's recorded voice, n=19), fetal HR data were collected using an ECG (Monica AN24) and a Hewlett-Packard Model 1351A CTG. Simultaneously, maternal HR data (n=37) were collected using the same ECG device (Monica AN24) and a second stand-alone cardiac monitor (Spacelab 514T cardiac monitor with a QRS detector).
  
  
  RESULTS
  During 20 min of maternal rest, correlations of individual fetal CTG with ECG measures of HR at each second were moderate to high (r=.57-.97) for 77% of fetuses. Correlations of HR averaged over fetuses and over each of the 20 min were high (r=.93-.97); fetal HR averaged over 20 min varied between devices from 0.0 to 0.8 bpm. During 2 min of maternal voice presentation, correlations of fetal HR over each second were moderate to high (r=.54-.99) for 95% of fetuses and high (all rs=.99) when averaged across fetuses in 30s or 2 min epochs. Average fetal HR between devices over the 2 min voice varied from 0.0 to 0.6 bpm. Correlations and/or % agreement between the two ECG methods of measuring maternal HR were high. Average maternal HR over 10 min showed 81% of pairs with a difference of ≤ 1 bpm; correlations for HR variability measures varied from r=.89 to .97.
  
  
  CONCLUSIONS
  Good reliability was demonstrated between individual spontaneous and auditory induced fetal CTG and ECG with high correlations when HR data were averaged over fetuses or in 30-120 s epochs. High reliability of maternal HR measures was obtained using two ECG devices.
authors.affiliation: School of Nursing, Queen's University, Kingston, ON, Canada; Department of Obstetrics & Gynaecology, Kingston General Hospital, Kingston, ON, Canada. Electronic address: kisilevb@queensu.ca.
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Kisilevsky
authors.affiliation: School of Nursing, Queen's University, Kingston, ON, Canada. Electronic address: browna@queensu.ca.
authors.forename: C Ann
authors.initials: CA
authors.lastname: Brown
mesh_terms: D015148:Cardiotocography / Q000379:methods; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005333:Fetus / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D008991:Monitoring, Physiologic / Q000379:methods*; D009035:Mothers; D011247:Pregnancy; D015203:Reproducibility of Results
keywords: Cardiotocograph; ECG; Fetus; Heart rate; Pregnant women; Reliability; Voice