Inverting during your period

The yoga instructors I have been taught by tell women not to do inversions during their period. Tonight in yoga we did shoulder stand.
If the instructor does not give an alternative pose I usually choose legs up the wall. Baxter gave us an alternative option tonight. It was almost like legs up the wall but without the wall. I chose to do that. It felt good. The bolster is an amazing tool to use during yoga practice.
In the Yoga Health Benefits article I found: “According to the traditional Yoga philosophy, menstruation is referred to as ‘apana.’ This refers to a downward flow of energy. Performing an inversion when one is experiencing ‘apana’ is thought to interfere with this natural flow of energy.” I have heard this before and I tend to follow this philosophy.
As I was researching for this blog post I found many articles, posts, etc. that said inverting during your period was fine. But all said the individual should decide what is best for her.
If you want to read more, you can go here, here and here. There are, of course, many more out there.