At 20 weeks the baby’s fetal heart is usually below the navel or slightly off, the fetus will keep moving in the womb, so the position of the fetal heart is not fixed. Pregnant women can go to the hospital or home to use the fetal heart monitor to detect the fetal heart, home testing note the following points: 1, environment: try to choose a quiet environment, pregnant women take a supine position, head slightly padded, legs straight, relax; 2, apply coupling agent: coupling agent has a lubricating effect, and as an ultrasound guide medium, conduct ultrasound signal. Try to apply evenly, should not be too thin or too thick; 3, looking for fetal heart position: the probe close to the abdominal wall, to use a little soft force, to prevent the probe and belly between the air caused by noise; 4, listening to the fetal heart: find the correct fetal heart position, after hearing the baby’s stable and continuous fetal heart sound, stand still for a period of time, so that the fetal heart rate probe to receive a stable and continuous fetal heart signal, the value of stable for the effective fetal heart rate. The normal fetal heart rate is between 110-160 beats per minute. If the fetal heart rate is obviously abnormal, it may indicate fetal abnormality, and you should consult a doctor in time.