Menstruation is a woman’s monthly normal vaginal bleeding, often called the period.
When a baby girl is born, her ovaries contain hundreds of thousands of eggs, which stay inactive until puberty begins.
There isn’t one right age for a girl to get her period but Most girls get their first period about 2 years after their breasts start to develop. when they’re between age 10 and 15 but it’s different, every girl’s body has its own schedule. two structures in the brain, the pituitary gland, and the hypothalamus produce complex hormones that stimulate the ovaries to make female sex hormones start and control The menstrual cycle. and it will continue to about age 51 . usually lasting from three to 8 days.