What are the “blood mysteries”?

There are books that go into this (like "Earth" by Barbara Marciniak) but I can give you the basics. The blood mysteries are mysteries that connect and bond womens’s lives to the Great Goddess from their menarche, to their menses, through childbirth, and then to menopause. With each of theses great transitions, the spirit of the women is transformed, expanded, and initiated into divine wisdom & knowing.