Factors that raise your risk of developing endometriosis include:

• Being between puberty and menopause (around age 50). After estrogen levels drop at menopause, endometriosis risk disappears. In the past it was thought that women could only have endometriosis after many years of menstrual periods, but this is not true. Endometriosis has been found in girls before puberty and soon after their first menstrual period.
• Family history in a mother or sister (first-degree relative), which makes severe endometriosis more likely. This risk appears to be inherited through the mother.
• Menstrual cycles of less than 28 days.
• Menstrual flow of longer than 7 days.
• Menstruation that started before age 12.
• Fewer than two full-term pregnancies.³
• An abnormal structure of the uterus, cervix, or vagina (usually present from birth) that blocks or slows menstrual flow.