The Gn initiation will evaluate the basal sex hormones and sinus follicle diameter to determine whether the standard for downregulation is met. Therefore, if ovulation promotion treatment is performed later, the primary node is to see if the standard for downregulation is met. During the course of the long protocol treatment, the endogenous Gn secretion is reduced to the minimum or even to the menopausal level due to the effect of GnRH agonist, and then exogenous Gn regulation can be used to achieve the final transfer of embryos according to the artificially controlled ovulation promotion and egg retrieval.