This painful condition affects between 10 to 15% of women, and is caused by tissue that normally lines the womb growing elsewhere in the pelvis.
Using mice, the team found excess iron promoted the rogue tissue growth.
The discovery that iron-binding molecules reduced cell growth might lead to treatments, say the scientists in the journal Human Reproduction.
Endometriosis is an often painful condition.
The menstrual cycle makes the wayward endometrial cells grow and break down as they would usually do in the womb, but the resulting internal bleeding, which has no outlet, can cause pain and scarring, sometimes leading to infertility.
So far, scientists have been puzzled about the causes of the condition.
But a team of scientists at the Catholic University of Louvain, Belgium, believed that iron could be to blame, because of the high-levels of iron found in sufferers pelvises’.
Some scientists believe the excess iron is created as the body breaks down the red blood cells from the monthly internal bleed.
To test their hypothesis, the scientists induced endometriosis in mice.
In some of the mice, they added iron-containing red blood cells, in others they added a molecule, desferrioxamine, which binds to iron and neutralises its effect, and the rest were left with endometriosis alone.
They discovered the numbers of lesions in the mice in the three experiments were approximately the same.
But they found the cell growth in the lesions were much greater in the mice with added iron than in the mice that simply had endometriosis.
By comparison, the mice treated with desferrioxamine had less cell activity than the other mice.
The team concluded that iron was causing increased cell growth in the mice.
Professor Jacques Donnez, lead author on the research and head of the department of gynaecology at the Catholic University of Louvain, said the use of iron-binding molecules might form the basis of future treatment for the condition.
He said: “Our findings represent a crucial step in finding the answer to endometriosis because we are focusing our research more on the origins and causes of the disease in the context of prevention, than on surgical treatment when the disease is already present.
“We really hope that, in the future, genetics will help us to determine the population of young women at high risk of endometriosis, and that treatment, resulting from our findings, may then prevent the development or evolution of the disease.”
Tony Rutherford, a spokesman for the British Fertility Society and a consultant gynaecologist at Leeds General Infirmary, UK, said: “Endometriosis is a condition which affects many women and is particularly prevalent in the Western world.
“It can cause a great deal of problems, from pelvic pain to infertility.
“This paper shows that iron may be a factor which stimulates the number of cells in the endometrial tissue.
“It is an important observation, but this is a mouse study, and you cannot always translate animal studies into humans, so further studies are needed to see whether this will truly be of clinical benefit.”