Endometriosis, cancer and giving birth link not proven
Never having given birth does not further increase the risk of developing cancer in women with endometriosis, research shows.
In the past it was thought that women with endometriosis who had never given birth had higher odds of developing cancer than those with child.
But this study confirms that having a baby does not affect the relationship between endometriosis and cancer.
Endometriosis, a condition where the lining of the womb grows outside the uterus, can increase women's risk of developing ovarian, kidney, endocrine and thyroid cancers.
Scientists at the Karolinska University Hospital in Stockholm, Sweden, studied 63,630 women who were diagnosed with endometriosis between 1969 and 2002.
Study author Anna-Sofia Melin says that future studies will hopefully lead to better patient care and to an early diagnosis should cancer develop.
Senior Information Officer Joanna Owens at Cancer Research UK said: "Our advice to women is to know your body, contact your doctor promptly if you notice any changes, and attend screening when invited."