In vitro fertilization-embryo transfer (IVF-ET) technology is the common term for the technique. It is an assisted human reproduction technique in which oocytes are removed from the woman’s ovaries, allowed to combine naturally with the man’s sperm in the laboratory to form an embryo, and then transferred to the mother’s uterus for implantation and pregnancy. It is called “IVF” because the test tube replaces the mother’s fallopian tube in the laboratory. With the increasing number of infertility patients, more and more people are choosing IVF to help them conceive, and the most important concern for those who undergo IVF is the success rate. The success rate of IVF is influenced by many factors. Age is the key factor influencing the success rate of IVF. 25-35 years old is the prime age for women to have children and the success rate of IVF is higher at this stage, but over 35 years old, the ovarian function of women declines significantly and the success rate of IVF will also decrease. 2. Infertility causes There are various causes of infertility, among which patients with infertility caused by endometriosis and polycystic ovary syndrome will have lower IVF success rates than other patients. Fluid in the fallopian tubes can also significantly reduce the embryo fertilization rate and pregnancy rate. 3. Endometrial thickness The endometrium is important for embryos and is an important place for embryo implantation. If the endometrium is thick enough, with rich blood flow and good cell division, it will increase the rate of embryo implantation, on the contrary, if the endometrium is too thin, embryo will not be easily implanted. If the endometrium is damaged, myometriosis, etc., it may cause the embryo to not be able to be bedded and affect the success rate. 4. Psychological state The influence of psychological state is also very crucial. Excessive psychological tension may cause endocrine disorders, which may lead to difficulties in embryo implantation, so infertile women should maintain psychological balance and be optimistic and open-minded during the IVF treatment. The quality of embryos is a key factor in the success rate of IVF, as high quality embryos are easy to succeed and poor quality embryos have a high failure rate. Clinically, the quality of embryos can only be distinguished by their morphology.