The uterus that develops before puberty is called the infantile uterus.Whether the uterus is infantile at the age of 14 is determined by whether or not menstruation is occurring, and most of the uterus is no longer infantile. From 4 weeks to 12 years of age, the child is called the childhood period. Before the age of 8, the hypothalamus-pituitary-ovarian sex hormone axis is in a state of inhibition, and the genitals are infantile during this period. From 10 to 12 years of age, the child gradually enters puberty, and the first menstrual period is an important sign of puberty. At this time, the uterine cycle is often irregular, but the reproductive organs will gradually develop. Most 14-year-old girls have menstruation, and their uterus is no longer strictly speaking infantile.