Early pregnancy, that is, within 12 weeks of pregnancy, when the uterus grows in the pelvic cavity, the fetal heart rate probe can not probe the fetal heart, temporarily can not find the fetal heart. If you use a fetal heart monitor to monitor the fetal heart, it is too early to detect, the uterus grows in the pelvic cavity, the probe of the fetal heart monitor is not able to detect the fetal heart, the uterus grows and expands and grows out of the pelvic cavity and enters into the abdominal cavity above the third month of pregnancy, the fetal heart can be heard in the lower abdomen. To monitor the fetal heart by yourself with a fetal heart monitor, try to wait until after 16 weeks of pregnancy. The position of the fetal heart varies with the age of the fetus. Before 6 months of age, the fetal heart is usually located in the midline of the abdomen below the umbilicus or on both sides of the midline, and the position of the fetal heart moves up as the fetus grows in size from 6 to 8 months of age. To monitor the fetal heart through the fetal heart monitor, it is necessary to find the location of the fetal heart to be able to accurately determine whether the fetal heart rate is normal. It is recommended to consult a specialist if there are any special conditions during pregnancy.