It is normal for a woman to have her menstrual cycle 7 days early or 7 days late. A woman with a menstrual cycle of 21-35 days is considered to have a normal menstrual cycle. Early menstruation can be caused by mood swings, nervousness or changes in the environment. Once a woman has early menstruation, there is no need to be too nervous. First of all, we should pay attention to whether there are recent environmental changes, mood swings, mental tension, etc. If these factors are excluded, frequent early menstruation may be considered a decline in ovarian function.