Hormone receptors line the inner cavity of the vaginal canal, the inner lining of the uterus and the ovaries. There are also triggers in the vaginal canal, cervix and uterine walls that communicate to the pituitary gland in the brain. Touching any of these areas (as vaginal steaming does) is going to trigger the hormone feedback loop. It’s also possible that the increased circulation produced by the heat of steam may directly influence the ovaries (as it appears to do in case studies where ovarian cysts spontaneously drained after steaming). Furthermore, clearing old residue from the uterine walls would also help the hormone receptors in the uterus and improve imbalances in the hormonal cycle.