The fertilized egg is formed after the union of sperm and egg. The fertilized egg will slowly develop into a gestational sac, and at 6-7 weeks of pregnancy the primitive cells of the gestational sac will differentiate to form an early fetal bud, which will further develop into a fetal heart, which is also the initial formation of a fetus. The germ is a stage in the normal development of the embryo. The first two weeks during the development of the fertilized egg is called the gestational sac, after which various organs are gradually formed, and until eight weeks it is called the embryo or germ. Because the embryo develops 30-40 days to form the gestational sac, 40-50 days to form the fetal bud, and 50-60 days to form the fetal heart. Therefore, an ultrasound is performed at about 60 days, or 8 weeks of pregnancy, to see if the gestational sac, fetal bud and fetal heart are normal. Of course, not all women appear at the same time, because there are a few women who, because of irregular menstrual cycles, late ovulation, late fertilization of the egg, etc., the appearance of the fetal bud and fetal heart activity will be relatively delayed, so in case no fetal bud is found in the first examination, you need to review it after a week. If no fetal bud or fetal heartbeat is found after 10 weeks of pregnancy, it should be considered that the embryo has stopped developing. Therefore, it is important for women to go to the hospital for an ultrasound on time after the pregnancy is confirmed, in addition to ruling out ectopic pregnancy, and to observe the development of the fetal buds. If necessary, blood tests for progesterone and HCG should be done, which are very necessary in early pregnancy.