Non-invasive fetal monitoring using radiotelemetry

A telemetry system for non-invasive monitoring of fetal heart rate and uterine contractions is described. Fetal heart information is obtained by means of Doppler ultrasound, and contractions information using an external tocodynamometer. The more important features of the device are described in detail; the full design is available from the authors. Typical recordings are presented, and the fetal heart rate traces are compared qualitatively with those obtained by direct ECG measurement, with the patient in bed, sitting and walking. The device is now in clinical use.