Causes of Ectopic Pregnancy

Ectopic pregnancies occur when the fertilized egg gets stuck on its way to the uterus. This is usually caused by damage to the fallopian tube which can leave it scarred. At other times the specific causes of an ectopic pregnancy remain unknown.

There are many risk factors that increase a woman’s chances of having an ectopic pregnancy. However, one must remember that even women who are not in any of these risk categories can have ectopic pregnancies. Some of these risk factors are:

  • Prior History of Ectopic Pregnancy: Women with a history of ectopic pregnancies runs a higher risk. The risk increases from 15% after the first ectopic pregnancy to 30% after the second.
  • Damage to the Fallopian Tubes: Women whose fallopian tubes have been damaged run a higher risk of ectopic pregnancy. Damage to the fallopian tubes can result in an alteration of the tube’s structure, making it easier for the fertilized ovum to get stuck on its journey to the uterus. The damage could have been caused due to several reasons. Prior surgeries like tubal sterilization or reconstructive surgery can lead to scarring on the inner surface of the fallopian tubes, as can infections, tumors or congenital deformities.
  • Infection: Women who have suffered from any type of pelvic inflammatory disease are also at risk of ectopic pregnancy. These types of infections are usually caused by sexually transmitted diseases like gonorrhea or chlamydia. However, they could also be caused by other bacteria as well. The infection causes damage to the cilia that line the inner surface of the fallopian tubes. These are hair-like projections on the inner walls of the fallopian tubes that help transport the fertilized egg smoothly through the fallopian tubes to the uterus. Damage to the cilia can cause the fertilized egg to get stuck, preventing it from reaching the uterus and causing an ectopic pregnancy. An infection can also result in the partial obstruction of the fallopian tubes which can prevent a fertilized egg from reaching the uterus.
  • Multiple Sex Partners: Women who have multiple sex partners have a higher risk of pelvic infection and therefore, a higher risk of ectopic pregnancy.
  • Other Conditions: Conditions like endometriosis and fibroid tumors can cause a narrowing of the fallopian tubes, thereby increasing chances of an ectopic pregnancy.
  • In-vitro Fertilization or IVF: On rare occasions, an ectopic pregnancy may occur simultaneously along with an intrauterine pregnancy. This is referred to as a heterotopic pregnancy. The incidence of heterotopic pregnancies is on the rise, primarily due to the increase in the use of IVF and other assisted reproductive technologies.
  • Cigarette Smoking: Women who smoke at the time of conception are at increased risk from ectopic pregnancy. The risk factor depends upon the number of cigarettes smoked.