If two yolk sacs are seen within one gestational sac, clinically it may be a case of identical twins. In this case, often as the pregnancy progresses further, transfusion between the fetuses may occur, so one embryo may stop developing, and it is recommended to always go to the hospital regularly for the corresponding obstetric examinations. In addition, blood tests for blood HCG are also recommended in this case. In the case of twin pregnancies, the blood HCG will appear correspondingly higher than in singleton pregnancies, which can be clinically diagnosed as a twin pregnancy basically. It is recommended to have regular maternity checkups during pregnancy and to strengthen the nutrition in order to facilitate the normal growth and development of the embryo.