Endometriosis affects one in 10 women of reproductive age in the UK, yet there’s limited research into what causes it.
The condition occurs when tissue that behaves like the lining of the womb is found in different areas of the body such as the ovaries, the lining of the pelvis behind the uterus and the top of the vagina.
The condition can cause sufferers to experience painful or heavy periods, pain during sex and fertility issues.
It takes (on average) seven years for women to get a diagnosis from the onset of their symptoms, according to health charity Endometriosis UK.
Here are eight famous women who have opened up about living with the condition, in a bid to raise awareness and help fellow sufferers seek diagnosis.