Abstract: The risk of ectopic pregnancy （EP） is higher in pregnancies resulting from assisted reproductive technology （ART） than in spontaneous pregnancies. Clinical studies showed that tubal factor infertility，different hormonal milieu，ART procedures，and embryo implantation potential were potential risk factors. At present, most reports were descriptive on the molecular mechanism of tubal ectopic pregnancy. Limited data revealed that some molecules may play roles in EP pathogenesis, which related to infection，hormonal abnormality and ART procedures. Those molecules may involve in the mechanism of embryo ectopic implantation through their impact on tubal transfer function，tubal environment and/or embryo factors. But, the changed expressions of those molecules could be simply the result of tubal implantation. Further understanding the aetiology and risk factors of tubal ectopic pregnancy is critical for us to improve ART procedures and prevent EP.

Key words: Pregnancy, ectopic, Pregnancy, tubal, Reproductive techniques, assisted, Risk factors