The implantation of a fertilized ovum outside the uterus but within the peritoneal cavity or in any tissue except that of the uterine wall: Ectopic pregnancy implies that the pregnancy is "in an abnormal place or position" where the most common site is the fallopian tube, the tube that normally carries eggs from the ovary to the uterus. In this case, ectopic pregnancy can also occur in the ovary, the abdomen, or in the cervical canal which is the opening from the uterus to the vaginal canal.

The terms "tubal pregnancy", "ovarian pregnancy", "cervical pregnancy", and "abdominal pregnancy" all refer to the specific areas of an ectopic pregnancy.