Abstract: Ectopic pregnancy（EP） remains the leading cause of maternal mortality in the first trimester of
pregnancy. The incidence of EP has been rising for several decades, so recognition of it′s risk factors could help to
facilitate early diagnosis, treatment and prevention. In the researches of our country and abroad, the associated risk factors
for EP mainly include pelvic inflammatory diseases （PID）, previous abdominal surgeries, cigarette smoking, previous EP, a
history of infertility, the use of assisted reproductive technique, the failure of contraception, abortion, and the the older
maternal age et al. And while PID, previous tubal surgery and cigarette smoking are considerd to be the most common three risk
factors. Yet, EP is always accompanied by one or more risk factors.

Key words: Ectopic pregnancy, Risk factor, Pelvic inflammatory disease, Surgery, Smoking, Contraception