Abstract: In vitro fertilization and embryo transfer（IVF-ET） is the important technology of human assisted reproductive technology（ART）. In recent years， the success rate of IVF-ET has been improved significantly along with continuous optimization in culture conditions of gametes and embryos. But the incidence of spontaneous abortion still remains. It is necessary to probe into the individual factors in patients with infertility and the process of IVF?-ET treatment services， with a view to discover the reasons for spontaneous abortion， in order to take preventive measures to improve the birth rate in IVF?-ET. This paper reviewed causes and preventive measures of spontaneous abortion of IVF?-ET.

Key words: Fertilization in vitro, Embryo transfer, Abortion, spontaneous