The exact cause of endometriosis is unknown, but there are several possible factors that may contribute to its development. Some of these factors include:

• Retrograde menstruation: This is when menstrual blood flows back through the fallopian tubes and into the pelvic cavity instead of out of the body. The blood contains endometrial cells from the inner lining of the uterus. These cells may stick to the pelvic walls and surfaces of pelvic organs.

• Immune system problems: A faulty immune system may fail to find and destroy endometrial tissue growing outside of the uterus. Immune system disorders and certain cancers are more common in women with endometriosis.

• Hormones: The hormone estrogen appears to promote endometriosis. Research is looking at whether endometriosis is a problem with the bodys hormone system.

• Genetics: Endometriosis may run in families, suggesting that there may be a genetic component to the condition.

• Structural issues: Having a structural issue with the vagina, cervix, or uterus that prevents the passage of menstrual blood from the body may increase the risk of endometriosis.

• Other factors: Other factors that may increase the risk of endometriosis include never giving birth, menstrual cycles occurring more frequently than every 28 days, heavy and prolonged menstrual periods that last longer than seven days, having higher levels of estrogen in your body, having a low body mass index, and starting your period at an early age.

Its important to note that having one or more of these risk factors does not necessarily mean that a person will develop endometriosis. Additionally, some people with endometriosis may not have any of these risk factors.