Teenage menstrual dysfunction: an overview.

When a girl experiences her first period, she starts a new phase of her life and becomes biologically capable of becoming a mother and giving birth to a child. Girls' hypothalamus-pituitary-ovary axis reaches "axial maturity" during puberty, when they are between the ages of 8 and 13 years old. Secondary biological features, including as growth, body-shape changes in females, breast growth, hair growth on the vulva, and hair growth on the axillary pits, are often observed during this era. The first menstruation, or menarche, is also commonly observed during this time. During the menstrual cycle, a woman's ability to conceive and give birth is at the core of her reproductive life.