The relationship between the yolk sac and the survival rate of the embryo is that with the yolk sac, the embryo may survive, but there is no authoritative statistics on the specific probability, but without the yolk sac, the embryo will definitely not survive. Fertilized egg in the uterus on the basis of the bed, only the embryo normal development of fetal heart, buds, it can continue to survive, otherwise, the embryo will gradually shrivel up and die shedding, accompanied by peripheral blood vessel rupture blood outflow from the vagina of the mother-to-be, that is, miscarriage. The yolk sac usually appears in the 5th-6th week of pregnancy, and according to the development of the embryo, usually within 1-2 weeks after the embryo has the yolk sac, the embryo will develop the fetal heart and buds. However, if the quality of yolk sac is not good, empty sac may appear, then the embryo is difficult to survive. In conclusion, the yolk sac is a prerequisite for embryo survival, but the presence of the yolk sac does not guarantee that the embryo will necessarily survive and develop normally, and there are no authoritative statistics on the survival rate of embryos after the presence of the yolk sac. From the 5th week of pregnancy onwards, the gestational sac, yolk sac, embryo bud and fetal heart appear sequentially. Therefore, pregnant mothers should grasp this developmental pattern, pay attention to ensure a balanced diet and nutrition during this period, emotional stability, avoid falls and other accidents, wait for the development of the embryo at ease, and follow the doctor’s instructions to carry out the relevant examinations on time.