In a small number of pregnancies, the fertilized egg attaches to an area outside of the uterus, rather than in the uterus. This is called an ectopic pregnancy or extrauterine pregnancy.

Nearly all ectopic pregnancies develop in a fallopian tube. These are often called tubal pregnancies. If left untreated, a tubal ectopic pregnancy can cause fallopian tube damage and cause heavy bleeding that could be deadly. So unless the pregnancy is miscarrying on its own, medicine or surgery is used to stop the pregnancy.

Ectopic pregnancy can also occur in an ovary, the cervix, or the abdomen. This is rare.