The main factors that determine the success of IVF are the quality of the embryo, the receptivity of the endometrium and the match between the two. Like the relationship between the seed and the soil, where the embryo is the seed and the endometrium is the soil, the match between the two is the right time to plant the seed. Therefore, to improve the success rate of IVF, we must prepare from these three aspects. Embryo quality Currently, embryo morphology and developmental rate are mainly evaluated, which is easy to perform and non-destructive. However, it is difficult to accurately predict the developmental potential of the embryo, with an accuracy of about 60-70%. 1. Morphological assessment: The clinical grading is based on the size and regularity of the oocyte, the refractive index of the cytoplasm and the number of fragments. The Bourn Hall Clinic in the UK (where the first IVF cases were born) classifies embryos into 6 grades: Grade 1: embryos with uniformly regular ovoid spheres, uniformly clear cytoplasm, intact zona pellucida, no or only a few fragments, <10%; Grade 2: embryos with less uniformly regular ovoid spheres, slightly altered refractoriness of the cytoplasm, intact zona pellucida, fragments <30%; Grade 3: embryos with ovoid spheres of Grade 3: fragmentation of the embryonic ovoid <50%, the rest of the ovoid is similar to that of grade 2 embryos, with intact zona pellucida; Grade 4: fragmentation of the embryonic ovoid >50%, the rest of the ovoid has the characteristics of a living cell. Grade 5: embryos with delayed fertilization or embryos developed by reinsemination the day after fertilization failure; Grade 6: embryos with inactive, degenerated, wrinkled and blackened oogonia. Generally, grade 1 and 2 embryos are considered as usable embryos, while grade 3, 4, 5 and 6 are not usable embryos. However, there are occasional cases of successful pregnancy after transfer of grade 3 and 4 embryos. 2. Growth rate assessment: The growth rate of embryos is generally judged by the number of oocytes in the embryo. 1: 42-44 hours after insemination, development to 4-5 cell stage; 2: 66-48 hours after insemination, development to 6-8 cell stage. It is generally believed that embryos with fast growth rate have high developmental potential. Before transferring the embryos, the quality of the embryos is taken into consideration and those with high developmental potential are selected for transfer, but the number of embryos should be limited to avoid the occurrence of multiple births. II. Endometrial receptivity There are no good indicators to assess endometrial receptivity, which is only based on endometrial morphology. According to the assessment based on ultrasonography, the endometrium is divided into three types: type A: the endometrial trilinear sign is obvious; type B: the trilinear sign is not obvious; type C: the trilinear sign disappears. Changes in endometrial morphology are generally monitored dynamically. As follicles continue to increase and estrogen secretion increases, the trilinear sign begins to appear and is most pronounced in the preovulatory period; after ovulation, progesterone is secreted, the endometrium transforms and the trilinear sign disappears. The endometrium with good receptivity usually changes from type A to type C. However, in clinical practice, it is found that some patients with type A still show the trilinear sign despite the presence of uterine adhesions, which masks the lesions inside the endometrium and misleads embryo transfer. In fact, the best diagnosis of the endometrium is if the patient with high quality embryos is not pregnant after transfer. Hysteroscopy is recommended in this group of patients to exclude endometrial pathology. According to my clinical findings, certain patients can develop uterine adhesions and cause embryo transfer failure despite the absence of pregnancy history and history of curettage. After treatment of hysteroscopic adhesion decomposition, embryo transfer was successful. Third, the right time for embryo transfer i.e. the embryo age should coincide with the endometrial age. For now, the high incidence of hysterosal adhesions is the main factor affecting IVF failure, and patients are advised to pay attention to the diagnosis and treatment of this problem. In summary, for patients who are ready to undergo embryo transfer, first of all, they should keep asking themselves if my endometrium is OK. If so, be prepared to schedule the embryo transfer. For patients who have repeated failures, it is important to take a moment to look carefully for the cause of the failure. Then, treat the infertility accordingly according to the cause. If you have any other questions, you can also communicate with me by applying for telephone consultation service, through which you can directly understand your condition in more detail and give clear consultation advice.