Fetal heart sounds can usually be detected by fetal heart monitor after 12 weeks of gestation. As the embryo grows and develops, primitive heart tube beats can be detected on ultrasound as early as the 7th week of gestation. Fetal heart sounds can be detected as early as after 12 weeks of gestation with a fetal heart monitor, a type of ultrasound Doppler monitor that checks fetal heart sounds. As the gestational weeks increase, the fetal heart sounds increase in intensity and are more easily detected. The monitoring of fetal heart sounds can help to understand the condition of the fetus in the uterus and allow timely detection of fetal hypoxia and intrauterine distress. In addition, the thickness of the abdominal wall of the pregnant woman and the position of the fetus can affect the detection of fetal heart sounds, and if the abdominal wall of the pregnant woman is thicker, it is more difficult to hear the fetal heart. In addition, the normal fetal heart rate should be above 120 beats per minute and below 160 beats per minute. If a pregnant woman checks her own fetal heart rate at home and finds that the fetal heart rate is outside this range, it is recommended to go to the obstetrics department of the hospital for examination and treatment.