In Chinese philosophy, yin–yang theory is the fundamental law of the universe. The inter-change between yin and yang explains everything. It applies to women’s menstrual cycle as well.
The balance between estrogen and progesterone ensures normal female reproductive ability. Disorders, such as irregular menstruation, endometriosis, even infertility, may occur when there is an imbalance between these two hormones.
Magically, there is a bridge over Traditional Chinese Medicine and conventional medicine. The changes of two hormones during different phrase of menstrual cycle correspond to the changes of yin and yang during each phrase. Details see chart:
