Fresh embryo transfer is performed after superovulation, which often causes multiple follicles to develop, resulting in high estrogen levels in the blood, and progesterone often rises prematurely. The excess physiological dose of estrogen and progesterone will cause a series of changes in the endometrium, resulting in early maturation of the endometrium and reduced synchronization with embryo development, which will affect embryo implantation. In contrast, frozen-thawed embryo transfer avoids the adverse effects of high estrogen and progesterone on the endometrium caused by superovulation, and the development of embryos, implantation and fetal growth are similar to natural pregnancy, which also significantly reduces ovarian hyperstimulation and the occurrence of ectopic pregnancy. In summary, the number of newborns born from frozen embryo transfer is increasing globally at a rate that greatly exceeds the number of newborns born from fresh embryo transfer, and there is a growing awareness of the benefits of frozen embryo transfer.