The success of IVF is related to the level of the medical institution, but a more important influencing factor is the physical state of the couple – especially the woman. The main reasons for IVF failure are the following links: 1. Failure of ovulation promotion The first step in IVF treatment is ovulation promotion. Women with normal menstrual cycles will generally have one follicle grow and ovulate per menstrual cycle. Ovulation treatment is the application of ovulation-promoting drugs to promote the growth of multiple follicles at one time during a menstrual cycle in order to obtain multiple eggs at one time and form multiple embryos. In general, older women have poor ovarian function, which means that the number of follicles in the ovaries is already low and the quality of these eggs in the ovaries is not very good, so the number of eggs obtained after ovulation treatment is low and the quality is also poor. In some women, with poor ovarian reserve, it is also easy to not get good eggs and embryos, which may also lead to failure. In addition, in women with polycystic ovary syndrome, ovulation is difficult due to abnormal follicle development, and sometimes the success rate is not high. For women with good ovarian reserve, if the timing of ovulation promotion is not good, or if they are sick, overly nervous or fatigued during the process of ovulation promotion, it may also lead to failure of ovulation promotion. Failed egg retrieval refers to a woman who has a certain number of follicles after ovulation, but the oocytes in the follicles are not successfully extracted. The chance of this is very low, about 1 in 1000. Generally when the number of follicles is very small, the chance of failed egg retrieval is relatively high. However, if the number of follicles is sufficient, it is rare that they will not be retrieved. However, there is a type of “empty follicle syndrome” that can lead to failed egg retrieval. The incidence is about 0.5%. The cause of empty follicle syndrome is unknown and it may occur repeatedly in individual patients. 3. Failure to form a fertilized egg After the egg is removed, it has to unite with the male sperm to form a fertilized egg. Failure at this stage is related to the quality of both the egg and sperm and cannot be easily predicted in advance. Many couples who fail in this part of the process often have investigated many years and programs to find the specific cause of their infertility. This indicates that the reason for their failure to conceive is most likely due to the poor quality of their eggs or sperm. This happens in about 3% of cases. The quality of the eggs has a greater impact on this link, but the sperm also has some influence. 4. Failure to form an embryo After the fertilized egg is formed it will develop and form an embryo, and then the qualified embryo will be transferred to the mother. This part depends on the quality of the fertilized egg. If the fertilized egg is not good, it will lead to the death of the fertilized egg during the in vitro culture process, resulting in the inability to obtain embryos and perform embryo transfer. 5. Embryo transfer failure Generally speaking, after embryo formation, the doctor will transfer the embryos on the 3rd or 5th day after insemination back to the mother’s uterus, this process requires a certain degree of skill from the doctor, and if the embryo transfer tube can be placed successfully, embryo transfer failure will rarely occur. 6.Pregnancy failure After embryo transfer to the mother, we have to wait for the mother to get pregnant. The failure rate of this session is relatively high, on average about 50% of women will show failure in this session. The main reasons for failure in this session are related to factors such as women’s mental stress, physical discomfort and luteal support medications.