Fetal heartbeat monitor is a kind of ultrasonic Doppler monitor to check fetal heart sounds, which can be detected as early as after 12 weeks of gestation, and it is also easier to be detected as the gestational weeks increase. At 18-20 weeks, the fetal heartbeat can be heard with an ordinary stethoscope on the abdominal wall of the pregnant woman, and the normal fetal heartbeat is 110-160 beats per minute. However, the thickness of the pregnant woman’s abdominal wall and the position of the fetus can affect the detection of fetal heart sounds, and if the pregnant woman’s abdominal wall is thicker, it is more difficult to hear the fetal heart. Therefore, the time when the fetal heart can be heard is slightly different for each pregnant woman. It is recommended that pregnant women follow the doctor’s advice and go to the hospital regularly for maternity checkups to monitor the changes in the fetal heartbeat and observe whether the fetal development indicators are normal, so as to ensure normal fetal growth and development during pregnancy.