The reason why women menstruate 5 days earlier is mainly related to the fluctuation of hormone level in the body, the reasons are as follows: 1, there may be luteal insufficiency caused by the low level of progesterone in the body will prematurely make the endometrium fall off. 2, it may be the endocrine disorders caused by the spirit, work activities, stress, menstruation will be early. Under normal circumstances, the menstrual cycle is an appropriate range of changes in the 21-35 days is normal, and each menstrual period within 5 days in advance is normal, if the menstrual period more than 7 days in advance is not normal. Normally, you should pay attention to maintain a regular life, eat a reasonable and nutritious diet, avoid smoking and alcohol, in favor of the balance of the endocrine system, if necessary, you need to go to the hospital to do gynecological diseases and sex hormone examination, according to the different causes of the use of medication to carry out treatment.