A ten year old girl who had her period last month and is late in coming this month is due to the fact that the gonadal axis is not yet fully established and the ovaries are not yet mature. Women usually have their first menstrual period at the age of 11 to 16 years old, and a ten-year-old girl’s menstruation is on the early side. At this time, the ovaries have not yet matured and cannot ovulate regularly, and the gonadal axis has not yet been fully established. Generally speaking, irregular menstruation occurs within two years after a girl’s first menstruation, so parents do not need to be overly concerned. If a woman’s menstruation is still irregular 2 years after menarche, it is necessary to consider the existence of endocrine disorders, and timely medical treatment is needed. It is recommended that menstruating women take good care of themselves during menstruation to prevent menstrual cramps due to cold stimuli during menstruation.