Menarche Medical Definition

Menarche defines the onset of menstruation, which is a normal physiologic process that occurs at regular monthly intervals. Menarche typically occurs around age 12 but a few years earlier or later is completely normal. Menarche happens during a time of physical and sexual maturation in adolescence known as puberty.

It is common for menarche to occur and then for a young girl not to get another period for a few months. This is because it can take a while for the hormone cascade that is responsible for ovulation and regular menstruation to mature.

Even if a girl’s menstrual cycles are not regular, they have still passed menarche because they have had their first period.

A young girl looking at her phone on her bed
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The Onset of Menarche

The onset of menarche is sort of predictable. Typically menarche will occur about 2 ½ to 3 years after the first appearance of breast buds. The time between breast buds and menarche is when girls may start to have problems with skin breakouts. It is also a time when girls can become moodier and start to talk back to their parents. A girl’s growth spurt typically happens a few months before menarche.

Menarche is a normal process of maturation in girls along with the other changes that happen to a girl’s body during puberty. The timing of menarche is important. If a young girl has her first period before the age of 8 she likely has a condition known as precocious puberty. This is not normal and needs further medical attention.

If a girl has had an otherwise normal development of her breasts and pubic hair but does not have her first period by the age of 16, she could also have a problem. This is known as delayed menarche or primary amenorrhea.

Delay of Menarche

Most likely the cause of this delay in menarche is due to continued interference with the hormonal cascade needed for menstruation to occur. This can happen in very athletic teen girls including ballet dancers and in girls suffering from eating disorders especially anorexia nervosa. Very rarely a girl could have a congenital absence of her uterus a condition called Mayer-Rokitansky-Kuster-Hauer Syndrome.

The onset of menarche marks the beginning of the reproductive years of a woman’s life. Actually beginning just before the first menstrual period a girl has had her first ovulation. It is actually that first ovulation that causes the first period or menarche. Once a girl ovulates she can get pregnant. It is important for girls to know that having sex even before they have had their first period could result in pregnancy.

Menarche is a normal process. It is a point in time that begins a woman’s reproductive years. In most women, it marks the beginning of regular monthly periods that will last until around the age of 52 which is typically when menopause is reached.

Also Known As: the first period, first menstrual cycle

Updated by Andrea Chisholm MD

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Lacroix AE, Langaker MD. Physiology, Menarche. In: StatPearls [Internet]. Updated April 15, 2019.

  2. Teens Health from Nemours. All about periods.

  3. McLean M, Davis AJ, Reindollar RH. Abnormalities of Female Pubertal Development. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA):, Inc. Updated August 19, 2015.

  4. National Organization for Rare Disorders. Mayer-Rokitansky-Küster-Hauser Syndrome.

By Tracee Cornforth
Tracee Cornforth is a freelance writer who covers menstruation, menstrual disorders, and other women's health issues.