Level 1: Success rate and failure reasons of in vitro fertilization In vitro fertilization is an assisted reproductive technology and is the hope of many infertile couples to realize their dream of having children. However, the success rate of in vitro fertilization is not high, only about 30%. There are many reasons for the failure of in vitro fertilization, including low ovarian function in women, poor sperm quality in men, and failure of embryo implantation. Level 2: How to improve the success rate of in vitro fertilization