There is no substitute for a fetal heart monitor without a coupler. The coupler increases the lubricity of the probe, which can slide more easily over the abdominal wall to find the fetal heart. It also reduces the air inside the space where the probe and skin surface come in contact with each other, thus increasing sound transmission, which facilitates better hearing of the fetal heart. No coupler can be purchased as soon as possible and then used. It is best not to use other items instead, so as not to affect the effect of listening to the fetal heart, resulting in a misjudgment of the results. Pregnant women can listen to the fetal heart at home by themselves, but they still need to pay attention to regular maternity checkups, observe the development of the fetus, and if there is any abnormality, they should consult the hospital in time for fetal heart monitoring.