Whipstitch Chronicles just published a nice blog reviewing information currently on the internet about the hazards of doing inverted postures while menstruating.
Overall, the blog was great, but I have an objection to one line.
The medical perspective has basically verified that there is no reason to fear that inverted poses during menses will increase a woman’s risk factor for developing endometriosis, a painful pelvic condition that can lead to infertility.
This is so not true.
I understand where she gets it. In the Yoga journals a medical doctor once quoted some (at the time – a decade or so ago) cutting edge research about the cause of endometriosis that pointed to factors other than retrograde flow as causative. The studies referred to determined that migrated stem cells within the pelvic cavity developed into endometrial tissue. Now we know those stem cells likely come from the endometrial layer of the uterus from retrograde flow. Others docs have said that most women have some backwards flow but that not all women develop endometriosis. Thats true. There are other factors working in concert, but retrograde flow is a risk factor and the more backward flow, the more likely one is to develop disease.
Although we still don’t really know for sure what makes some women have the disease and not others, Samspons 1927 theory of retrograde menstruation remains the prevailing scientific hypothesis for what causes endometriosis. Its complicated, and other factors play a part- things like genetics, epigenetics, immune function, environmental toxins like dioxins, etc.
For sure, women who have more frequent periods, those who bleed heavier, and those with a blockage to normal flow through the vagina are the most likely to develop endometriosis. That indicates the amount of backward flow is important in development. Quantity matters. Baboon studies back this up the more endometrial tissue in the pelvic cavity, the more likely you are to develop disease.
“While there are no studies looking specifically at whether or not women who practice inversions during their periods are more likely to develop endometriosis (arguably a very difficult study to really do well), prudence is wise. Anyone with a personal or family history of endometriosis should never do inversions while on their period. Other women need to be careful too, especially during the days of heaviest flow. If they choose to invert during menses, then time in the posture should be limited to one minute.”
The longer time spent inverted and the heavier the flow, the more likely there is to be retrograde drainage of endometrium into the pelvic cavity. The presence of endometrial cells in the pelvic cavity in sufficient quantity increases the risk for endometriosis.
These consequences, of course, arent observable right away. You may feel fine right after spending 20 minutes in sirsasana during the time of heaviest menstrual flow, but youve possibly just begun a cascade of changes that ultimately lead to a debilitating and painful disease, one that often leads to infertility.