What is Menarche?

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  • Written By: wiseGEEK Writer
  • Edited By: O. Wallace
  • Last Modified Date: 19 April 2019
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Menarche, which can be pronounced as men-are-key, is more commonly known as first period or first menstruation. It usually does not mean that a girl has had her first ovulation, which typically follows first bleeding. Yet it is a symbol and a suggested likelihood that a normal pattern of ovulation will soon be established, resulting in menstruation approximately once a month.

Age at which menarche occurs differs among individuals, and may be different in varying populations of the world. There are many things that might influence time of first period, and these include percentage of body fat, and environmental and psychosocial factors. One factor that is said to account for the gradual change in age of menarche in whole populations like that of the United States is obesity. It is known that, as a whole, the age of first period has fallen in the US, with more girls experiencing their first period earlier. Scientists are quick to point out that there is more than one reason that could account for this shift.

In countries like the US, average age of first menstruation is under 13 years, but these statistics aren’t really about individual likelihood of getting a period sooner or later. Instead, they are analysis of huge numbers of girls, who can express great variation. Many girls do not start their period until they are several years older than 13, and others may reach menarche when they are 9 or 10.


One predictor does seem to be body fat; reliably young women who don’t have enough body fat to ovulate will not get or continue periods until they are older. For small framed, extremely athletic girls it’s not unusual for menarche to be delayed by several years past age. Additionally extremely dedicated athletes may experience their periods stopping, called amenorrhea.

A debate that exists continually when a first period occurs is whether ovulation occurred before it. The answer is not completely satisfying. Ovulation may occur before it, meaning that there is some likelihood of pregnancy prior to a first period.

While it would be hoped that young women would not have to think over this issue, some do, and in other cultures, culturally approved sexual activity may begin much sooner. Even when the general culture or a child’s parent does not approve of very young teens or pre-teens engaging in activity of this nature, that doesn’t keep it from occurring. Given these facts, parents planning to involve their children in any form of sexual education should consider starting before menarche.

In addition to considering the practical aspects of first menstruation, many people view this an emotional or spiritual time and may celebrate it in some fashion. Adolescents often look forward to and wait for this day, seeing it as a time when they progress to womanhood. They may keep score of who has gotten their period and who hasn’t. A thriving culture of urban legends can abound for girls interested in this topic, and parents should help verify a daughter understands what menarche actually means.

There may be real ritual in celebrations, especially in many native cultures, but in the Western world, each family may create their own rituals, and some ignore the matter completely. For parents and guardians, though, there may be something both sweet and sad about menarche. It signifies that on a basic, physical level, the change from little girl to woman is in progress, though it is by no means complete.


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