1, age Age is the most important factor in determining the success rate. The gradual decline of ovarian function as women age is an inevitable trend, a process that is difficult to reverse. In most cases, the decline of ovarian function starts at the age of 35, becomes obvious after the age of 38, and worsens after the age of 42. The decline in ovarian function indicates that the number of eggs retrieved by IVF is low and the quality of eggs is poor, which may lead to the possibility of no embryo transfer. Therefore, it is recommended to abandon IVF for those older than 45 years because the success rate is very low, less than 5%. The success rate of IVF for those younger than 35 years old can reach 40%-60%, 30%-40% for 35-38 years old, 20% for 38-42 years old and 10% for 42-45 years old. Ovarian Reserve Function The ovarian function can be assessed by the blood hormones and the number of sinus follicles measured by ultrasound on the 2nd-3rd day of menstruation of the natural cycle. There are individual differences in ovarian function, therefore, doctors need to assess the patient’s ovarian function before formulating a plan. Patients with a high number of sinus follicles, low basal FSH levels, good ovarian function, and uncomplicated uterine pathology have a high IVF success rate. 3, uterine factors The IVF success rate is lower in patients with combined uterine pathology, such as uterine adhesions, submucous fibroids, uterine mediastinum, history of endometrial tuberculosis, endometritis and repeated scraping to endometrial thinning. Hydrosalpinx affects embryo implantation because the trapped fluid can flow into the uterine cavity. Hysteroscopy can accurately evaluate and treat uterine lesions. Vaginal ultrasound to see the endometrial blood flow is an assessment of the normal uterine cavity lining, which can predict the success rate of high-quality embryos after transfer. 4. Lifestyle and psychological factors Unhealthy lifestyle and unstable emotions are detrimental to the success of IVF, such as smoking, drinking and staying up late. Excessive tension, anxiety and depression are also another reason for failure. Therefore, before and after IVF, you should maintain a healthy lifestyle and try to be relaxed, happy and confident. For patients who have difficulty in managing their emotions or have psychological distress, it is recommended to go to a psychological counseling office for counseling.