A period of 25 days is within the normal range. A woman’s normal menstrual cycle is 22-35 days, and any normal menstrual cycle within this range indicates a normal menstrual cycle. A woman’s menstrual cycle is calculated from the first day of the last menstrual period to the day before the next menstrual period. Women’s menstruation is under the control of the cerebral cortex, so it may fluctuate due to various factors, including environmental changes, changes in sleeping habits, emotions, life stress, work stress, and other factors. A woman’s menstruation is within the normal fluctuation range of seven days early or late and does not require any treatment. If the menstrual cycle is less than 21 days it is called early menstruation and is mostly caused by insufficient luteal function. If menstruation is often delayed, always absent, or even comes only once in 2-3 months, endocrine disorders should be considered and relevant tests are recommended.