You may have heard that it is unsafe to invert during your period, and perhaps you have even questioned the validity of such claim. Usually the concern is that inversions could cause retrograde menstruation (back flow of menstrual blood to the fallopian tubes and further into the pelvic cavity) and lead to endometriosis - a condition in which endometrial tissue (the cell tissue lining your uterus) grows in other areas of your pelvis and can lead to inflammation and possible complications (Sampson’s theory, 1927).
Across the literature on the subject of retrograde menstruation (RM) AND endometriosis (EDM) - it hasn’t been determined that RM causes EDM. One study concluded that 90% participants investigated had RM without EDM (Halme Et al, 1984). Whilst other studies concluded that prevalence of RM is higher in investigated participants with EDM compared to those without - so the take home from this is you could have RM but it doesn’t mean you have EDM. Hooghe Et al, 2002, discussed how congenital, cycle characteristics and immunological factors can play a role in EDM. Also of interest, Kunz et al, 2002 discuss uterine contractile dysfunction and the possible causation of EDM.
If gravity pushes your menstrual flow out, then would microgravity (such as in space) would push it back in? Uterine contractions controlled by your autonomic nervous system are the mechanism behind your menstrual flow, not gravity. Sally Reid is the first recorded female astronaut to go into orbit during her period. When preparing for her mission, NASA had asked Reid, if 100 tampons would be the right number for a short mission...she replied, “No, that would not be right”. Interestingly, female astronauts are more attractive to go into space as they require less resources than their male counter parts, but NASA were more concerned with the associated psychological temperament of a female astronaut during her period....
It is said, in subtle yoga anatomy (relating to chakras, nadis, meridians) that inversions disrupt the downward energy known as ‘apana’ - one of the 5 primary directional energies. An inversion could be classified as any position where your pelvis is elevated higher than your head - so this would rule out headstand, shoulder stand etc, but by this logic, downward facing dog, wheel pose and standing forward fold would also be contraindicated as your pelvis is tilted forwards/upside down - rarely have I heard this purported in a class. Thus, the concept of 'apana' can be a justification for not inverting during your period. But must we remain upright during menstruation to facilitate apana? What happens when you’re horizontal? Think about it, you’re spending more time (hours) laying horizontal than you are being in that shoulderstand....
To conclude - our periods can be a sensitive time, with hormone levels fluctuating, causing an array of uncomfortable symptoms from digestional complaints, migraines to lethargy to name just a few commonly experienced symptoms.
Employ your self enquiry - feel and do what is right for YOU. A strenuous practice involving inversions may feel great and may even alleviate your symptoms, OR you might opt for a more gentle approach and even skip yoga altogether. I certainly have been known to miss my practice and instead demolish several, yes SEVERAL Ritters Rum Raisin bars - not squares but BARS. If you’re unsure, leave the inversions out and if you’re concerned go speak to an appropriately qualified health care practitioner. Do the research, don’t be entrenched in Dogma. As teacher Gina Caputo said;
“Much of what we’ve learned from traditional yoga is based in a deeply antiquated view of menstruation and dictated by people who have never experienced menstruation.”