Fetal heart rate monitoring using the abdominal fetal electrocardiogram.

An evaluation of a prototype abdominal fetal electrocardiogram (ECG) module for use in a Sonicaid FM3R monitor is described; 103 antenatal recordings of fetal heart rate (FHR) were attempted in 56 patients between 21 and 43 weeks gestation. The overall success rate was 54 per cent but the proportion of successful recordings was reduced between 24 and 36 weeks gestation. Most successful recordings were obtained with the first electrode placings and the quality of the recordings was generally higher than those obtained by simultaneously recorded FHR from ultrasound. Monitoring using the abdominal ECG during parturition was found to be unreliable. The advantages of the method are that it is non-invasive, the patient is not restricted by belts and the technique is easy to apply. However the uncertainty of obtaining a FHR trace between 24 and 36 weeks gestation is a major disadvantage.