Leukorrhea is a normal taste, which is a mixture of vaginal secretions and cervical secretions. Normally, the vagina is in an acidic environment with a pH value of ≤4.5. This acidic environment is the result of the combined action of Lactobacillus and estrogen. Estrogen thickens the epithelial cells in the vagina and increases the amount of glycogen in the cells. Lactobacillus vaginalis can break down glycogen into lactic acid, thus maintaining an acidic environment in the vagina. This acidic environment can inhibit the growth of other pathogens, which is called the self-purification of the vagina, and can make the female vagina have a defensive function.