The signs before menstruation in elementary school students are accelerated growth and development, sudden acceleration of height growth, sudden growth, gradual expansion of breast development, like a small ball, the areola is obviously enlarged, the nucleus of the breast is obvious, and there may even be swelling and pain. There will also be a small amount of pigmentation in the perineum and the sprouting of a small amount of short, fine downy hair. Most students have their first period, also known as menarche, at the age of 13-14. Slightly earlier elementary school students may have their period at 11-12 years of age, but no earlier than 10 years of age, and if they have their period before 10 years of age it is called precocious puberty. It is also not later than the age of 16. If the first menstruation does not occur at the age of 16, or even at the age of 20, it is called delayed menstruation. In these cases, whether it is earlier than 10 years old or later than 16 years old, you should take your child to an endocrinologist for further examination and search for the cause, and then intervene and treat the child under the guidance of a professional doctor.