—Kathleen Heitler, California Barbara Benagh's reply: First of all, there is no consensus on whether to avoid inversions during a woman's menstrual cycle. The two opinions are basically divided between those who think that no women should practice inversions during menstruation and those who feel the choice varies from woman to woman. Those who encourage a ban on inversions cite fears that certain physical problems may arise. Until recently, increased risk of endometriosis was considered the most common risk. But since more is known now about that disease, the idea has been debunked. There is also a theory that inversions may cause "vascular congestion" in the uterus resulting in excessive menstrual flow. If true, this risk is probably most relevant for women who hold inversions a long time. Some teacher’s say that since a woman's energy is low during menstruation, high-energy poses such as inversions should be avoided.
This makes sense, yet not all women experience low energy during menstruation; indeed, many feel quite energized. Philosophically speaking, menstruation is considered to be apana, meaning that energetically, its vitality is downward-flowing. The argument against inversions during menstruation maintains that inversions will disturb this natural energetic flow. However, inversions are recommended in some systems of yoga as therapy to improve elimination of excess apana. In Yoga: The Path to Holistic Health, B.K.S. Iyengar recommends practicing inversions to alleviate menstrual problems such as heavy flow and irregular periods. The contradictions don't stop there. Some teachers recommend avoidance of inversions such as Sirsasana (Headstand) and Sarvangasana (Shoulderstand) while suggesting no such caution with other poses that invert the uterus, such as Uttanasana (Standing Forward Bend) and Adho Mukha Svanasana (Downward-Facing Dog). Since I know of no studies or research that makes a compelling argument to avoid inversions during menstruation, and since menstruation affects each woman differently and can vary from cycle to cycle, I am of the opinion that each woman is responsible for making her own decision. Pay attention to how you respond to inversions (indeed, ALL asanas) during your period. A short Headstand may be fine
while a longer one isn't; maybe you will find that backbends or twists adversely affect your period. If your energy is very low, restorative poses may be just the ticket, though you may find a more active sequence of standing poses alleviates cramps and the blues. You really won't know what works and what doesn't until you feel it in your own body. The bottom line is that hatha yoga is full of contradictions and varied opinions, leaving each of us ultimately responsible for our own choices. Pay attention to your body and discover what works and what doesn't—not just during your period but every day.