Causes
There are a number of risk factors for ectopic pregnancies. However, in as many as one third to one half no risk factors can be identified. Risk factors include: pelvic inflammatory disease, infertility, use of an intrauterine device (IUD), previous exposure to DES, tubal surgery, intrauterine surgery (e.g. D&C), smoking, previous ectopic pregnancy, and tubal ligation.
Although older texts suggest an association between endometriosis and ectopic pregnancy this is not evidence based and current research suggests no association between endometriosis and ectopic pregnancy.
Read more about this topic: Ectopic Pregnancy