(HealthDay News) -- Endometriosis is a condition in which tissue that resembles uterine lining grows outside the uterus. Symptoms may include pain, infertility and very heavy periods.

The National Women's Health Information Center offers this list of common risk factors for endometriosis:

• Starting your period at a young age.
• Having very heavy periods.
• Having periods that last more than seven days.
• Having a short monthly menstrual cycle of 27 days or fewer.
• Having a close relative who has the condition.