Fetal heart can be detected on 47 days of normal pregnancy, this refers to the patient’s normal menstrual cycle, the menstrual cycle is about 28 days once, if the usual menstrual cycle is inaccurate and delayed, this time even if the pregnancy is 47 days old, may not be able to detect the fetal heart, this case may be due to the prolongation of the menstrual cycle, the pregnancy has not reached 47 days, it is recommended that one week later to go to the ultrasound to check again. If the gestational sac is relatively large and the fetal heart cannot be seen, this case should also be considered whether it is the result of embryonic arrest, normal pregnancy around 42 days may be able to see the fetal buds and the fetal heart, if the normal pregnancy 47 days did not detect the fetal heart, it is recommended that a week later to review the ultrasound. If the size of the gestational sac is more than 2.5cm, and there are no buds or fetal heart, there is a clinical indication that the embryo may have stopped developing.