The endometrium is the tissue that lines the uterus and sheds during menstruation. In endometriosis, tissue similar to endometrial tissue is found outside the uterus. Scientific research has been unable to pinpoint the reason why some women develop endometriosis. There are a number of yet-unproven theories about what might cause endometriosis:

• During menstruation, endometrial tissue may back up through the fallopian tubes into the abdomen where it attaches and grows.
• Endometrial tissue may travel and implant through blood or lymphatic channels, similar to the way cancer cells spread.
• Endometriosis may be present in female fetuses during gestation, and the condition is activated at puberty as estrogen levels increase.
• Cells in any location may transform into endometrial cells.
• In some women, endometriosis may develop after cesarean section (C-section) surgery when endometrial tissue is transplanted into the abdominal wall.

Research is ongoing to find the root cause of endometriosis.

Risk Factors for Endometriosis

Any girl or woman can develop endometriosis, but some have a higher risk than others. Scientists have identified several risk factors that raise the likelihood of developing endometriosis.

Hereditary Factors

Researchers believe there is a genetic component to endometriosis. Women who have a close relative (mother, sister, or daughter) with endometriosis are seven to 10 times more likely to have it themselves, according to a Yale University study published in 2008. A British study also found identical twins had matching endometriosis symptoms. White women are more likely to be diagnosed with endometriosis than those of other ethnic backgrounds.

Personal Health Factors

Most women with endometriosis are diagnosed in their 20s and 30s. Women who give birth for the first time after age 30 and those who have never given birth have a greater risk for developing endometriosis. Those whose periods began at an early age and those who go through menopause at a later age may be more at risk. Similarly, women with menstrual cycles shorter than 27 days may have a higher risk. Anatomical abnormalities of the uterus can predispose some women to develop endometriosis, as can any medical condition that prevents menstrual flow from leaving the body normally.

Environmental Factors

Research has shown a link between dioxin exposure and the development of endometriosis in monkeys. Dioxin may be produced during the manufacturing of pesticides or other chemicals, plastics, and paper products. Dioxin can contaminate food and accumulate in the food chain, especially in the fatty tissue of animals. Studies indicate that greater degrees of dioxin exposure resulted in more severe cases of endometriosis.

Can Endometriosis Be Prevented?

Currently, there is no way to prevent endometriosis. However, you can reduce your chances of developing endometriosis by lowering the levels of estrogen in your body. Estrogen levels can be lowered in several ways. Hormonal birth control keeps estrogen at a steady level in the body, preventing spikes and drops of hormone levels. Getting regular exercise, eating a low-fat diet, and maintaining a healthy weight help control estrogen levels.

Limiting your daily intake of caffeine and alcohol may also help reduce your risk for developing endometriosis.

Does Endometriosis Go Away on its Own?

About 1 in 3 women with mild endometriosis find their symptoms go away on their own. While endometriosis symptoms lessen with menopause for most women, this is not always the case, since the body continues to produce some estrogen. Endometriosis treatments and pregnancy can temporarily relieve symptoms, but they may reappear after treatment is stopped or after giving birth.

Condition Guide

• What Is Endometriosis?
• Adenomyosis vs. Endometriosis: Are They One and the Same?
• Endometriosis — The Path to Diagnosis
• Stages of Endometriosis
• Symptoms of Endometriosis
• Treatments for Endometriosis