Where you find the heartbeat can be due largely to the baby's position. Also, your uterus is still below your belly button until about 20 weeks so finding your baby's heartbeat low on your belly will be quite common until later in the second trimester. My doctor used to use it later in the pregnancy to tell whether the baby was head down. Basically if the heartbeat is heard under the belly button, then the baby was head down. Above the belly button means the baby is breech. Its likely that you will often find your baby's heartbeat in the same spot.