Fetal heart rate (FHR) is a type of ultrasound Doppler monitor that checks for fetal heart sounds, which can be detected as early as after 12 weeks of gestation, and gradually increases in intensity as the weeks of gestation increase, and is also easier to detect. At 18-20 weeks, the fetal heartbeat can also be heard on the abdominal wall of a pregnant woman with an ordinary stethoscope, and the normal fetal heartbeat is 110-160 beats per minute. However, the thickness of the abdominal wall of the pregnant woman, fetal position and other factors can affect the detection of fetal heart sound, if the abdominal wall of the pregnant woman is thicker, it is more difficult to hear the fetal heart. Therefore, there is a slight difference in how long a pregnant woman can hear the fetal heartbeat. It is recommended that pregnant women follow the doctor’s advice and go to the hospital for regular checkups to monitor the changes in the fetal heart and observe whether the developmental indicators of the fetus are normal, so as to ensure that the fetus grows and develops normally during pregnancy.