Endometriosis - Risk Factors

Risk Factors

Endometriosis affects at least 5.5 million women in North America and millions more worldwide. An estimated 2 - 4% of all premenopausal adult women have detectable endometriosis, and over a third of these women experience noticeable pain. Because many women with endometriosis have no symptoms, the actual percentage of premenopausal women with the disorder may be as high as 15%. Some experts believe endometriosis may be responsible for between 45 - 70% of chronic menstrual pain in adolescence.

Age. Endometriosis can occur in women of all ages. It has been reported in girls as young as age 8 (and has been documented before the onset of menstruation), and in women over age 75, with the average age being between 25 and 29. About 40 - 60% of women with endometriosis report symptoms before age 25.

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Ethnic Groups. Endometriosis is most common among Asian women, with Caucasians next. It is reported least frequently in African American women.

Heightened Menstrual Effects

Women at higher risk for endometriosis tend to have more problems with menstruation. Those at higher risk have a shorter than normal cycle, heavier periods, and longer periods. Heavier, more frequent periods, or longer exposure may simply make the risk for retrograde menstruation more likely. (This is the condition in which menstrual flows backward and is believed to be at least partially responsible for the initial development of endometriosis.) Menopause usually brings an end to mild to moderate endometriosis, although if women with a history of endometriosis take hormone replacement therapy (HRT), the condition may be reactivated.

Not Having Children

Not having children has been associated with a greater risk for endometriosis. Some evidence suggests that early pregnancy may be protective against endometriosis because the cervix becomes dilated during labor, which reduces the risk for retrograde menstruation (menstrual backflow).On the other hand, endometriosis itself can increase the risk for infertility, so it may be a cause rather than a result of not having children. Some studies have found no protection against endometriosis with pregnancy, although women with the condition find relief from symptoms during pregnancy.

Family History

Some experts report that almost 7% of first-degree female relatives of endometriosis patients also develop it. A family history of endometriosis not only puts women at high risk for the condition but possibly a more severe manifestation of it as well.

Uterine Abnormalities

Women may also be at higher risk for endometriosis if they were born with uterine abnormalities that obstruct the normal outflow of blood and cause retrograde menstruation.

There have been reports of endometriosis developing after cesarean sections, including implants developing in surgical scars and in the urinary tract. Some experts believe endometriosis should be suspected in women with urinary tract symptoms and a history of cesarean section.