Editing Menarche (section)

===Onset===
When menarche occurs, it confirms that the girl has had a gradual [[estrogen]]-induced growth of the [[uterus]], especially the [[endometrium]], and that the "outflow tract" from the uterus, through the [[cervix]] to the [[vagina]], is open.

When experiencing menarche, the blood flow (colloquially described as having one's "period") can vary from a slow and spotty discharge to a consistent blood flow for 3–7 days. The color of the blood ranges from bright red to brown in color; this is normal. Periods may be light or heavy.<ref>{{Cite web |date=2021-01-27 |title=First period: Early signs, how long it lasts, and self-care tips |url=https://www.medicalnewstoday.com/articles/first-period |access-date=2022-03-21 |website=www.medicalnewstoday.com |language=en}}</ref>

In very rare instances, menarche may occur at an unusually early age, preceding [[thelarche]] and other signs of puberty. This is termed ''isolated premature menarche'', but other causes of [[vaginal bleeding]] must be investigated and excluded.<ref name=AMN>{{cite web |author1=R. Stanhope |author2=C. Traggiai |title=Isolated Menarche |work=Precocious Puberty (Complete, Partial) |url=http://www.health.am/gyneco/more/isolated-menarche/ |year=2006 |publisher=Armenian Health Network |access-date=2006-11-26}}</ref> Isolated premature menarche is rarely the first manifestation of [[precocious puberty]].{{citation needed|date=March 2021}}

When menarche has failed to occur for more than three years after thelarche, or beyond 15 years of age, the delay is referred to as [[primary amenorrhea]].