If the yolk sac and germ are not seen in the examination, consider the following aspects: 1. The number of weeks of gestation is less than 6 weeks, the pregnancy is short, the embryo is small and in the stage of embryonic development, which is normal. 2. If the yolk sac and germ are not seen after 6 weeks of pregnancy, consider the abnormal development of the yolk sac, which is related to life rules, such as prolonged exertion, mental anxiety or irregular diet, nutritional deficiency, etc. 3. It is recommended to review the dynamics of ultrasound regularly and test the rise of blood HCG and progesterone to understand the development of the fetus. It is recommended that pregnant women should develop good living habits and relax during pregnancy, pay attention to a balanced diet, do the corresponding checkups, pay attention to rest and avoid overwork.