The physical process begins with the at the base of the brain. Around the ages of 11 to 17, this gland sends hormones to the ovaries, signaling them to mature an egg and the uterus to build up a thickened, velvety lining of blood and fluid.

: Many learners first navigate the practicalities of periods during physical activities. Some stories recount the "horror" of wearing a pad while swimming or the eventual realization that tampons or menstrual cups are better suited for active sports like dancing.

Many first-period stories involve a mix of surprise and the need for quick adaptation:

The transition into puberty and a person’s first period (menarche) is a natural biological milestone often shared through "period stories" that mix science with personal experience.