Failed implantation is when an abnormality occurs at some point prior to the process of establishing this close connection between the embryo and the endometrium, resulting in the failure of the embryo to implant. A biochemical pregnancy is one in which the embryo has begun to implant, the trophoblastic ectoderm has invaded the metaplastic layer of the uterus, and the beta-HCG secreted by the embryo enters the maternal bloodstream and reaches detectable levels, except that for some reason the pregnancy does not continue thereafter and the beta-HCG in the blood or urine is only transiently elevated. It is called a biochemical pregnancy because the pregnancy only proceeds to a stage where it can be detected by biochemical methods and does not progress to a stage where the gestational sac can be diagnosed by ultrasound, and can be considered a special type of early pregnancy loss. Miscarriage, on the other hand, is an event that occurs after embryo implantation and is a clinical pregnancy loss. Thus, failure of implantation, biochemical pregnancy and miscarriage all fall under the category of embryo or pregnancy loss, but occur at different physiological stages and are not the same thing. Abnormalities at any stage of embryo development and the process of implantation can lead to impaired implantation. Due to the complexity of the process and the fine tuning of many factors, it is not possible at this stage to identify the exact cause of each failure, which is mainly due to maternal factors, embryonic factors, and abnormalities in the dialogue between the two. The failure of IVF is a very heavy blow to the patient, from full of hope to dashed dream, the psychological frustration and stress is imaginable. For them, in addition to facing this failed outcome, they are more concerned about the chance of success if they receive the next treatment. DeNeubourg et al. found that patients who had early embryo loss had more high-quality embryos and frozen embryos and were more likely to have a successful next IVF, and Levy et al. also found that compared to the total IVF population, patients who had a biochemical pregnancy or miscarriage were significantly more likely to be able to go on to the next IVF. Pearson et al. found that those who had a biochemical pregnancy or miscarriage in the first cycle were more likely to have a live birth with IVF than those who had a failed first cycle. Although IVF failure is something that neither physicians nor patients want to see, it is important to carefully analyze the specific reasons for failure. The causes, mechanisms, and processes of miscarriage, biochemical pregnancy and miscarriage are all different, and should be treated individually and symptomatically for each case to give the next IVF treatment a better chance of success.