It is common for a fetal heartbeat to be detected between 6-8 weeks of pregnancy. However, it can vary depending on various factors such as the position of the fetus and the accuracy of the ultrasound equipment used. If an abdominal scan did not show a heartbeat at 6 weeks and 3 days, it is possible that it may be too early to detect it. Your healthcare provider may recommend a follow-up scan in a week or two to monitor the progress. In some cases, transvaginal ultrasound may be performed for better visibility in early pregnancy. It is important to remember that every pregnancy is unique, and it is best to consult with your healthcare provider for personalized guidance and reassurance during this time.