Every woman is different. Regarding myself (Anu Visuri, Gotta Joga's yoga teacher), I
don’t notice anything even if doing a handstand during my
period. I know women who say that inversions may cause a stop to
the bleeding and then make the bleeding stronger and with cramps
afterwards. If you have a painful or heavy bleeding during your
period, then it is better to avoid inversions, intensive
backbends and abdominal muscle exercises and in general any
intensive asana practice. Better to practice yin yoga or
restorative yoga in that case (Note- Gotta Joga Evening).
Downward facing dog however, may relieve menstrual pain so it
can be done without concern. Twists and forward bends are also
good asanas during the period.
In fact, the banning of yoga or certain asanas
during the period is originally a male invention, and certainly
cannot be generalised to all women.We women need to learn to
listen to our body and learn what is good for us and what not.
Every yoga style or school have different rules: e.g. in
ashtanga yoga women are forbidden to do an asana practice during
the first 3 days of her period, Iyengar forbid the inversions
and backbends during the period and abdominal exercise as a
whole from women. No man can know the female body as well as a
women herself. And that is exactly why to practice yoga: to get
to know our body and mind.