The causes of slow follicular development are as follows: first, problems with the pituitary gland in women, which is a relatively common cause of ovarian dysplasia. Secondly, premature ovarian failure, because the ovaries are needed for follicle development, after premature ovarian failure is not able to maintain follicle development, and can lead to abnormal menstruation, or even amenorrhea. Third, with polycystic ovary syndrome, the ovaries become larger and produce smaller follicles. The follicles will not develop to maturity and external drugs are needed to promote follicle development. Fourth, it may be a combination of medical system diseases, such as abnormal thyroid function, severe anemia or suffering from immune system diseases, all of which may cause abnormal follicle development. Fifth, it may be related to mental and health factors, if mental stress is high or excessive weight loss leads to weakness, causing endocrine disorders, it may affect the development of follicles.