It is not normal for a girl to have her period at the age of 9, and precocious puberty is suspected. The age of menarche is between 13 and 15 years old. The age of menarche is between 13 and 15 years old. Each child’s constitution is different, and the age of menarche has a lot to do with genetics, personal nutritional intake and constitution, but it will not be earlier than 11 years old, and the delay will not be more than 16 years old. Girls who menstruate at the age of 9 may have precocious puberty, and it is recommended that they go to the hospital in time for intervention and treatment. In addition, in order to avoid precocious puberty in children, it is important to avoid adding hormone-containing foods to the diet, and it is not recommended to give children too much anti-seasonal vegetables and fruits, as many of them use hormone-containing drugs to promote ripening. In addition, it is also necessary to carry out physical exercise to maintain a normal body shape, to avoid obesity, obesity may also cause precocious puberty.