Endometriosis occurs when endometrial cells (that normally line the womb) grow outside of the uterus for example on the ovaries or bowel. The condition is more common in older women or those who have not yet had pregnancies. The use of the oral contraceptive pill is protective against endometriosis.
Endometriosis affects fertility in a number of ways including egg development, ovulation, fertilisation and implantation. If identified, endometriosis can be treated (both surgically and medically) to improve pregnancy rates from spontaneous conception or via assisted reproduction (e.g. ovulation induction or IVF).
Aside from fertility issues, endometriosis may cause pelvic pain (often related with periods or intercourse), or some women may have no symptoms at all.