Firstly, a distinction should be made between early menstruation and shorter menstrual cycles within the normal range. A menstrual cycle of 21 days or more is considered normal as long as it is regular, with periods of 2 to 8 days and a volume of 20 to 60ml. If your menstrual cycle is shorter than 21 days, you are having an early period.
The common cause of early menstruation is luteal insufficiency, which needs to be confirmed by a basal body temperature test and endometrial biopsy. Various endocrine disorders, metabolic abnormalities, ovulation with assisted reproduction techniques, repeated miscarriages, as well as menarche, post-birth and menopausal transition are also prone to luteal insufficiency. Some organic diseases of the reproductive system, such as inflammation and tumours, may also present with early menstruation. Therefore, if you notice that you are experiencing early menstruation, you should visit a hospital promptly to identify the cause and treat it accordingly.
In addition, mental factors, prolonged poor emotional state, irregular work and rest, and excessive stress in life can lead to endocrine disorders in women, which may manifest as early menstruation.