The reason for 5 days early menstruation in women is mainly related to the fluctuation of hormone level in the body, for the following reasons: 1. It may be caused by the presence of luteal insufficiency, low progesterone level in the body will prematurely make the endometrium shed. 2. It may be due to endocrine disorders caused by mental, work activities and stress, and menstruation will also be early. Under normal circumstances, the menstrual cycle has an appropriate range of variation, between 21-35 days is normal, and each menstruation within 5 days in advance is normal, if the menstruation is more than 7 days in advance is not normal. You should pay attention to keep a regular life, eat a reasonable and nutritious diet, avoid smoking and alcohol, which is conducive to endocrine balance, and if necessary, go to the hospital for gynecological diseases and sex hormone examination, and use medication according to different causes.