The moon has always been the primary symbol for female energy; its cycle around the earth takes approximately twenty-nine days, the same amount of time as the average woman’s menstrual cycle or moon time. It is often felt that as the pull of the moon affects the waters of the world, so does its motion affect the body of woman.
A women’s blood and hormonal cycle follows the ebb and flow of the moon; from new moon to full moon, estrogen increases leading to ovulation, or maximum fertility, at full moon. From full moon to new moon, the waning half of the cycle, progesterone predominates. Traditionally, women used to start bleeding right before the new moon, in the dark of the moon.
In modern times, women begin their menstruation during different phases of the moon. Their bodies are out of sync with the moon and their spirits have forgotten the meaning of Grandmother Moon. One way to get back in harmony with the moon is by performing ceremonies and rituals at different times during the moon cycle and also by honoring the time of menstruation.
When a woman begins her monthly bleeding, she has a very special vibration. The blood flow is cleansing as the old uterine lining is sloughed off, one monthly reproductive cycle is ended. At menstruation, women have the chance to rid themselves of all old thoughts, habits, desires, and be receptive to new visions and inspirations for the next cycle. This is the dark moon phase.
If a woman continues her normal routine at menstruation, then she loses a uniquely female opportunity for introspection. She also finds she gets more tired, irritable, and upset because her physical rhythm has slowed down. She needs rest, more time for meditation, and less time doing housework, cooking, working in the outside world, and taking care of children.
In many Native American tribes and other tribal cultures, there is a separate moon lodge to which all women go. Since most of the women menstruated at the same time (have you noticed women who live together bleed together) during the dark of the moon, the grandmothers and fathers took care of the children. Food was left outside the lodge several times a day. Women during menstruation were/are considered to hold a certain power and not allowed to mingle with the rest of the tribe. Many tribes have taboos against these women, believing that their power would interfere with the hunt or take away the power of the medicine bundles.
This is also why women are not allowed in sweat lodges and must stand outside the circles in other ceremonies when they are in their moon time. We know now that women were also segregated because of fear of the immense power which enabled them to bleed each month and never die -the greatest of all the Mysteries- while a male warrior might succumb quickly after losing so much.
Source: Women’s Medicine Ways’ Cross-cultural rites of passage by Marcia Starck