Obstet Gynecol 105 (5 Pt 1): 1052 - 1057, 2015. doi: 10.1097/01.AOG.0000158860.26939.2d Etiology of Ectopic Pregnancy Most ectopic pregnancies are located in the fallopian tube, and any history of infection or surgery that increases the risk of tubal adhesions or other abnormalities increases risk of ectopic pregnancy.