In women with regular menstruation before pregnancy, the fetal bud is usually visible during the 6th week of gestation and the fetal heart is visible during the 7th week of gestation during an ultrasound examination. The time of appearance of the fetal heartbeat and fetal bud varies significantly among individuals and is related to the pre-pregnancy menstrual cycle. In women with regular menstruation before pregnancy, the fetal sac is usually visible in the 5th week of pregnancy, and the fetal heart and germ are visible in the 6th and 7th weeks. If menstruation and ovulation are delayed, the fetal heartbeat and fetal buds may be seen at the latest in the 8th week of pregnancy. If the time of ovulation is earlier, the fetal heartbeat and fetal buds may appear earlier, and in some cases, the fetal heartbeat and fetal buds may appear as early as the 5th week of pregnancy. Therefore, in order to clarify whether the embryo is developing normally, it is recommended to have an ultrasound examination and HCG test in the 6th-8th week after menopause, and if embryonic dysplasia, embryonic arrest or ectopic pregnancy is detected, appropriate treatment should be given in time.