A fetal doppler is a hand-held ultrasound transducer used to detect the fetal heartbeat for prenatal care. It uses the Doppler effect to provide an audible simulation of the heart beat. Some models also display the heart rate in beats per minute (BPM).

Fetal monitor also called maternal and infant monitor, it is a sensor used to monitor the physiological data of mothers and babies. It can sense various physiological changes, amplify and strengthen the information, and then convert it into electrical information, and then calculate and edit the information. If the specified index is exceeded, it will trigger an alarm system.