A mains electricity (AC-powered) device designed to detect, measure, and display foetal heart activity during the perinatal period. Typically foetal heart rate is measured, but heart valve movement can also be assessed. The device operates noninvasively by: 1) electronically registering and graphically presenting foetal heart sounds; 2) discriminating foetal and maternal electrocardiographic signals obtained from the maternal abdomen with external electrodes; or 3) transmitting and receiving ultrasonic energy into and from the pregnant woman usually by means of continuous wave (Doppler) echoscopy. The device may include an alarm that signals when the heart rate crosses a pre-set threshold.