Domiciliary fetal monitoring via telephone. A preliminary report

A cardiotocograph with autocorrelation system, a simple telephone amplifier, a telephone handset with adjustable speaker volume and an adapted portable ultrasonic fetal heart detector can form a simple but effective system for long distance telemetry of the fetal heart rate from patients' homes using public telephone network. Especially the combination of supervision and direct communication with the patient during registration reduces the loss of signal to a minimum (4%), resulting in a high percentage of correctly transmitted fetal cardiograms.