It may be a normal sign for an 11-year-old to have her period once and then stop. Because the endocrine system of 11-year-old girls is not developing stably, they are prone to irregular menstruation. The tissues and organs of 11-year-old girls are not yet fully developed, so the endocrine system is not particularly stable. If the phenomenon of having one period and then stopping occurs, it may be a normal physiological phenomenon. This is because the endocrine system is not stable, resulting in irregular menstruation. Parents do not need to worry too much, and regular observation is sufficient. As a girl grows older and her reproductive system, such as the ovaries, continues to develop, the endocrine system will gradually stabilize and menstruation will become regular. However, if an 11-year-old girl experiences symptoms such as increased menstrual flow and menstrual cramps, it is recommended that she go to the hospital in time.