The age of menarche is most often around 13-14 years old in girls, but it can be as early as 11 years old or delayed by around 16 years old. Menstruation is mainly controlled by genetic factors, and other factors such as nutrition and weight also play an important role. In recent years, there has been a tendency to advance the age of menarche. The first menstrual period is called menarche. The age of first menstruation is around 13 to 14 years old, but it can be as early as 11 years old and as late as 16 years old. failure to menstruate after the age of 16 should be taken seriously. Early menarche means that the child has menstruation before the age of 9 and may have precocious puberty, while late menarche may have primary amenorrhea. In the case of abnormal menarche, it is advisable to consult a doctor to identify the cause and intervene.