There are mixed ideas on the subject but here's a Yoga Journal article which might help you to make u your mind.
"Inversions and Menstruation
While practicing inversions when you have your period probably won't cause endometriosis as previously thought, it's still not a good idea for reasons having to do with vascular congestion.
By Yoko Yoshikawa
According to Mary Pullig Schatz, M.D., it is not true that inverting during menses causes endometriosis. The classic theory was that endometriosis is caused from "retrograde menstruation," in which bits of menstrual endometrium go up the fallopian tubes, lodge in the pelvic cavity, and grow, says Dr. Christiane Northrup, author of Women's Bodies, Women's Wisdom (Bantam Doubleday Dell, 1998). Schatz states that this theory is outdated, and that "it is now known that endometriosis arises from the presence of cells in the pelvic lining that are capable of developing into endometrial-type cells." Schatz does advise against inverting while menstruating, however, because it may lead to vascular congestion: The uterine veins, which are thin, can stretch and partially collapse, while uterine arteries continue to pump more menstrual blood into the uterus. If inversions cause you to bleed more than usual during your period, you may become weak and emotionally vulnerable."
For details, read "A Woman's Balance: Inversions and Menstruation," by Mary Pullig Schatz, M.D., at
http://www.iyengar.ch/Deutsch/text_menstruation.htm.
Asanas (poses) are one limb of the the eight limbs of yoga practice, which include breathwork, meditation, and the yamas and niyamas. Though the effects of asana practice may be immediate in some cases, asanas will reveal their true power through patient, long-term commitment to the practice.
Here is a list of recommended poses during menstruationn:
Adho Mukha Svanasana (Downward-Facing Dog)
One of the most widely recognized yoga poses, Downward-Facing Dog is an all-over, rejuvenating stretch.
Ardha Chandrasana (Half Moon Pose)
The moon has a rich symbolic significance in yoga mythology. In hatha yoga, for example, the sun and the moon represent the two polar energies of the human body. In fact, the word hatha itself is often divided into its two constituent syllables, ha and tha, which are then esoterically interpreted as signifying the solar and lunar energies respectively (don’t forget though that Sanskrit hatha literally means “force”). There’s also a subtle structure in the head (sometimes located at the back of the throat, other times at the base of the brain) called the “moon,” that secretes the “elixir of immortality” (soma or amrita), highly prized by yogis.
Ardha Matsyendrasana (Half Lord of the Fishes Pose)
Named after a legendary teacher of yoga, this twist energizes the spine and stimulates the digestive fire.
Dhanurasana (Bow Pose)
This pose is so called because it looks like an archer's bow, the torso and legs representing the body of the bow, and the arms the string.
Janu Sirsasana (Head-to-Knee Forward Bend)
A forward bend for all levels of students, Janu Sirsasana is also a spinal twist.
Marichyasana III (Marichi's Pose)
Marichi's Pose is sometimes called the Sage's Pose. Usually the pose is described with the arm to the outside of the bent knee, but this position isn't accessible to most students. Here we'll work with the arm hugging the leg that's bent.
Matsyasana (Fish Pose)
Unlike many of the poses that mimic the creatures they’re named after, Fish Pose doesn’t actually look like a fish. Instead, it’s said that if you perform this pose in water, you will be able to float like a fish.
Padmasana (Lotus Pose)
The ultimate yoga pose, Padmasana requires open hips and consistent practice.
Pasasana (Noose Pose)
In the full pose the arms are wrapped around the squatting legs and the hands are clasped behind the back, forming a "noose."
Paschimottanasana (Seated Forward Bend)
Literally translated as intense stretch of the west, Paschimottanasana can help a distracted mind unwind.
Setu Bandha Sarvangasana (Bridge Pose)
This active version of Bridge Pose calms the brain and rejuvenates tired legs.
Supta Padangusthasana (Reclining Big Toe Pose)
Supta Padangusthasana provides relief from backache and stretches the hips, hamstrings, and calves.
Supta Virasana (Reclining Hero Pose)
Reclining Hero or Heroine Pose intensifies the stretch in the thighs and ankles of its upright precursor. It also creates new stretches in the front groins–the area between the tops of the thighs and the hip points–the psoas muscles, and the deep hip flexors.
Caution: Supta Virasana, the reclining variation of Virasana, is an intermediate pose. DO NOT perform this pose unless you can sit your buttocks relatively easily on the floor between your feet.
Ustrasana (Camel Pose)
Camel Pose is a transition between the simpler prone backbends like Dhanuranasa (Bow Pose) and the more challenging backbends like Urdhva Dhanurasana (Upward Bow Pose). For this pose you can pad your knees and shins with a thickly folded blanket.
Utthita Parsvakonasana (Extended Side Angle Pose)
This pose creates a stretch along the top side of the body, from the back heel through the raised arm. What’s often neglected is the need to match the stretch along the under-side of the torso.
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