1. Producing Menses
The menses is one of the physiological characteristics of the female. Generally, during the period of 14 to 49 years of age, females have the physiological changes of menstruation every month, i.e., "the menses come on schedule." Menstruation belongs to the physiological function of the uterus. This development of the female body possesses the regular changes, along with the prosperity or decline of kidney-qi. When the essential qi of kidney is enriched to a certain extent, the substance tiangui is produced. When tiangui reaches a certain level, its promoting action influences the uterus to develop to maturity, ensuring proper menstruation and adequate conditions for conception and childbearing. In old age, the changes of physiological function have taken place, along with a decrease of the kidney essential qi, which causes menstruation to gradually cease, and the reproductive function to be lost.

In addition, menstruation is also closely related to the Chong Meridian and Ren Meridian (Conception Vessel.) Both belong to the extra meridians and start from the uterus, and are in close relation with the occurrence of menstruation; hence, they are also affected and regulated by tiangui. The Conception Vessel joins with the three yin meridians of the foot in the abdomen, and regulates all the yin meridians of the body. Thus, the Conception Vessel is referred to as "the sea of the yin meridians." When the tiangui arrives, the qi and blood of the Chong Meridian and Conception Vessel freely flow and become abundant, and empty into the uterus to produce menstruation. Thus, there are sayings that, "The Conception Vessel dominates the nourishment of the fetus," and
"The Chong Meridian is the sea of blood." In aged people, tiangui decreases, and the qi and blood of the Chong Meridian and Conception Vessel become insufficient, causing menstrual irregularity and eventual menopause. In clinical practice, dysfunction of the Chong Meridian and Conception Vessel may lead to pathological changes of menstruation, leading to disorders of the menstrual cycle, amenorrhea, and so on.