Stethoscope to listen to the fetal heart has a special stethoscope head, listen to the heart or lung stethoscope head is flat, disc-like, and listen to the fetal heart stethoscope head is called bell-type stethoscope, the head is standing up and has a certain height, like a bell, there is a trumpet and has a certain height. At present, more stethoscopes are bi-directional, while with a disk, the other side with a bell-shaped stethoscope, there is a switch button in the middle, as long as the channel and the direction of the switch, with the bell-shaped stethoscope can listen to the fetal heart. Listen to the fetal heart is usually in the lower part of the umbilicus, due to the gradual growth of the fetus, the position is different in the early, middle and late pregnancy, usually in the lower part of the umbilicus, and later in the umbilical circumference, whichever is the clearest position to hear the fetal heart.