How is a fetal heartbeat related to the risk of miscarriage?

Hearing the fetal heartbeat can be a reassuring sign for any pregnant woman. It means that the fetus is alive and that the pregnancy is most likely developing as it should. Since most miscarriages take place in the early weeks of pregnancy, detecting a sure sign of life lessens one's chances of having a miscarriage. Yet, a fetal heartbeat that is beating at a slower rate than expected may mean a miscarriage is inevitable.