During natural pregnancy, the follicle collapses after ovulation, forming the menstrual corpus luteum, which secretes progesterone. At this time, the endometrium changes from the proliferative endometrium under the dominant action of estrogen to the secretory endometrium, which is tolerant and conducive to embryo implantation. After fertilization and implantation of the expelled egg, the corpus luteum continues to enlarge under the hCG secreted by the embryonic trophoblast and transforms into the gestational corpus luteum, which continues to secrete progesterone to maintain the pregnancy until After 3 months of gestation, the placenta forms and secretes hormones to maintain pregnancy. In contrast, luteal insufficiency is present during the IVF cycle, thus requiring exogenous drugs to support embryo implantation after embryo transfer (equivalent to the luteal phase of the natural pregnancy process), a process called luteal support. The GnRH agonists or antagonists used for descending regulation in the IVF cycle inhibit the pituitary function, blocking the pulsatile release of LH, leading to luteolysis, and supraphysiologic amounts of estrogen suppress LH levels, leading to luteal hypoplasia and premature luteal degeneration. All of these reasons cause luteal insufficiency, which is not conducive to embryo implantation, so luteal support is needed after IVF transfer. Luteal support drugs include: progesterone, hCG and GnRH-a. The most commonly used drugs are progesterone, which are divided into intramuscular progesterone, vaginal progesterone gel and oral progesterone. The dose, duration of use and method of reduction of luteinizing support drugs should follow medical advice.