Most girls grow pubic hair before menstruation. The growth of pubic hair signals the development of secondary sexual characteristics, and it is only after the development of secondary sexual characteristics that the function of the ovaries will be gradually perfected, and the ovaries will secrete estrogen and progesterone periodically, causing cyclic changes in the endometrium before menstruation occurs. Due to individual differences, some people will have menstruation first and then grow pubic hair, although relatively few, but there will be such a situation, and not all women will grow pubic hair, and some will not grow pubic hair throughout their lives, mainly due to individual differences. In addition, once a girl has her period, she must strengthen the localized care of the vulva and strengthen the care of the menstrual period.