Who is at risk for getting endometriosis?

An estimated 2% to 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% and 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 10 and in women over 75, with the average age being between 25 and 29.

Approximately 40% to 60% of women with endometriosis report symptoms before age 25.

ETHNIC GROUPS.

It appears to be most common among Asian women, with Caucasians next.

It is reported least frequently in African American women.

GREATER EXPOSURE TO MENSTRUATION

Women at higher risk for endometriosis tend to have greater exposure to 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.

ASSOCIATED MEDICAL CONDITIONS

Various disorders occur in greater rates in women women endometriosis. In some cases, these disorders and endometriosis may be caused by common factors, but it is not clear what they are. They include the following:

• Certain cancers, particularly for early-onset breast and ovarian cancers, non-Hodgkin's lymphomas, and melanoma.
  
• Autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis. These are uncommon disorders, but in a major 2002 survey of women with endometriosis, they occurred in 12% of these women. This provides some support to the theory that endometriosis, too, is an autoimmune condition.
  
• Hypothyroidism. In the same 2002 survey mentioned above, 42% of women had hypothyroidism or some other hormonal disorder.
  
• Fibromyalgia and chronic fatigue syndrome. In the same survey, 31% reported one of these conditions.
  
• Diabetes.
  
• Allergies and asthma. Endometriosis is also more prevalent in women with a family history of asthma and allergies, including food and skin allergies and hay fever.

OTHER FACTORS ASSOCIATED WITH ENDOMETRIOSIS

Some studies have reported a higher incidence of certain factors in women with endometriosis:

• Women with endometriosis tend to be taller and thinner than average.
  
• Women with red hair have an increased risk for endometriosis; experts guess that the gene determining red hair might be located near other genes that make such women susceptible to endometriosis.

Alcohol and caffeine use have been associated with a higher risk.