Using tampons and having sex appears to protect women against developing endometriosis, a painful condition that affects about 10 million in America and often results in infertility, according to a study by a Yale physician.

Endometrial tissue normally grows only in the uterus and is shed each month during menstruation. Women who have endometriosis have the tissue growing in the Fallopian tubes, ovaries and other areas within the pelvis, and in rare cases, outside the pelvic area.

It is found in choldless women, or women who have children late in life. Women with shorter menstrual cycles and longer periods are also believed to be at higher risk of endometriosis.

"Our study has an important public health message for women, espacially at a time when many women seeking infertility care have endometriosis as their primary diagnosis," said Harvey Kliman, M.D., lead author of the study. "Our study suggests that tampon use could be one of the strongest protectors against endometriosis."

The study looked at whether sexual activity, orgasm, tampon use and douching during menstruation has an effect on the risk of endometriosis.

Douching during menstruation didn't appear to lessen a woman's risk of developing the condition, but the researchers found that sexual activity, orgasm and tampon use seemed to be linked to lessening the risk of developing it.

A back up of menstrual fluid in the pelvic cavity is currently believed to be the main cause of endometriosis, Kliman says. They believed that sexual activity, orgasm, tampon use and douching would enhance retrograde flow and heighten the chances of developing endometriosis.

To our surprise [these] were found to be less frequent among women with endometriosis compared to controls," Kliman said. "It may be that uterine contractions that are part of the female orgasm induces more effective menstrual fluid clearance of the uterine cavity, which in turn may facilitate cervical outflow. Further, the use of tampons may be more fficient at the removal of menstrual fluid compared to the use of pads."

[via Aphrodite]