There is a possibility of miscarriage if your baby's heartbeat stops after 12 weeks of gestation. However, if you have not heard your baby's heartbeat before 6 weeks, that doesn't always mean a miscarriage. Your doctors may want you to wait for another two weeks to find the heartbeat and see if the pregnancy is viable. In some cases, if there was a heartbeat and it suddenly stopped, it could mean you have had a miscarriage.