Menarche is considered early if it occurs at or before ten years of age and late if it occurs at or later than 15 years of age. Of specific concern is when menarche occurs too early, too late, or not at all, as these scenarios have future adverse outcomes. Secondary amenorrhea is the absence of menses for greater than three cycle intervals or six consecutive months in a previously menstruating female. Primary amenorrhea is the complete absence of menstruation by 15 years of age in the setting of normal growth and secondary sexual development or the absence of menses by age 13 in the absence of normal growth or secondary sexual development.

The absence of normal menstrual periods, unrelated to pregnancy, is termed amenorrhea.

It is a marker of normal female reproductive health and wellness. Most females recognize menarche as their body’s critical declaration of fertility. Menarche occurs in the setting of a maturing hypothalamic-pituitary-ovarian (HPO) axis and relies on the following processes: normal hypothalamic and pituitary function, normal female reproductive anatomy, normal nutrition, and the general absence of other intervening chronic illnesses.