Several factors place you at greater risk of developing endometriosis, such as:
- Never giving birth
- Starting your period at an early age
- Going through menopause at an older age
- Short menstrual cycles — for instance, less than 27 days
- Heavy menstrual periods that last longer than seven days
- Having higher levels of estrogen in your body or a greater lifetime exposure to estrogen your body produces
- Low body mass index
- One or more relatives (mother, aunt or sister) with endometriosis
- Any medical condition that prevents the normal passage of menstrual flow out of the body
- Reproductive tract abnormalities
Endometriosis usually develops several years after the onset of menstruation (menarche). Signs and symptoms of endometriosis may temporarily improve with pregnancy and may go away completely with menopause, unless you’re taking estrogen.
The main complication of endometriosis is impaired fertility. Approximately one-third to one-half of women with endometriosis have difficulty getting pregnant.
For pregnancy to occur, an egg must be released from an ovary, travel through the neighboring fallopian tube, become fertilized by a sperm cell and attach itself to the uterine wall to begin development. Endometriosis may obstruct the tube and keep the egg and sperm from uniting. But the condition also seems to affect fertility in less-direct ways, such as by damaging the sperm or egg.
Even so, many with mild to moderate endometriosis can still conceive and carry a pregnancy to term. Doctors sometimes advise those with endometriosis not to delay having children because the condition may worsen with time.
Ovarian cancer does occur at higher than expected rates in those with endometriosis. But the overall lifetime risk of ovarian cancer is low to begin with. Some studies suggest that endometriosis increases that risk, but it’s still relatively low. Although rare, another type of cancer — endometriosis-associated adenocarcinoma — can develop later in life in those who have had endometriosis.