Menarche, the first menstruation

The term menarche refers to the first cycle or first menstrual period, an event that in most cases occurs between the ages of 10 and 16. Symptoms include light bleeding, cramps and mood swings. This event marks an important milestone in the woman’s life: the beginning of the stage where she is able to become pregnant.

From the Greek menòs , “month”, and archè “beginning”, the menarche is defined as the first menstrual period in a female adolescent.

This is an important milestone, which marks the beginning of fertility: the beginning of ovarian activity and the woman’s reproductive life.

Getting your period means being physically able to get pregnant and have a baby, unless health conditions prevent it.

Anyone with a female reproductive system — meaning the vagina, uterus, fallopian tubes, and ovaries — can have periods. Cisgender girls, transgender boys, and non-binary people with female reproductive systems can also get periods.

What does it mean to have menarche

The first cycle occurs when the woman’s body is mature enough to support the menstrual cycle.

Each month the ovaries produce an egg and the lining of the uterus thickens. In case of sexual intercourse the oocyte can be fertilized. A fertilized egg travels to the uterus and implants itself in the lining of the uterus, where it grows into a fetus.

Anytime a woman has sex, she can get pregnant, even when she’s on her period. If the oocyte is not fertilized, the unfertilized oocyte and the lining of the uterus that was not used for fertilization are shed with the menstrual flow.

The first cycle

Having your first period has not only to do with the possibility of getting pregnant, but also with the changes that occur in the body and the adaptation to them.

These changes require figuring out which products to use to manage blood flow and, in some cases, address period-related symptoms. Products to manage blood flow include pads or panty liners, tampons, menstrual cups.


With your first period, it’s a good idea to start tracking your periods on a calendar, planner, or app. Tracking your periods can help you understand what is and isn’t normal for your period.

A normal menstrual cycle occurs every 21-35 days – 28 days on average – and lasts 3-7 days – 5 days on average. But every woman’s cycle is different.

For the first year or two, periods may be unpredictable. Then, as your period becomes more predictable, it makes sense to start watching for any abnormal bleeding and know what to do if it occurs.

Difference between menstruation and menarche

The menstrual cycle is a monthly sequence of events that prepares your body for potential pregnancy, and periods are only one part of the menstrual cycle.

Menarche, on the other hand, is the first period, and this makes it unique. The first cycle is not only the beginning of the fertile age in women, it is also an important marker of physiological puberty.

Before menarche, you may have noticed these changes in your body:

  • breast development;
  • pubic hair growth;
  • armpit hair growth;
  • growth spurt;
  • oily skin and acne.

The body may continue to grow after the first cycle, but most of the changes that puberty brings about happen earlier.

Age at which menarche occurs

Mean age of onset

Menarche typically occurs between the ages of 10 and 16, with a mean age of onset of 12.4 years. It is believed that:

  • socioeconomic conditions;
  • genetics;
  • general health;
  • nutritional status;
  • environmental factors;
  • exercise;

play a role in timing. For example, the first period may occur early in overweight girls, or late in, for example, underweight girls or girls who engage in vigorous physical activity.

One way to predict when your first period is coming is to look at changes in your breasts: Menarche usually occurs 2 to 2.5 years after your breasts begin to develop.

How to delay first period

In the case of confirmed early puberty, it is possible to stop puberty with injections of gonadotropin-releasing hormone (GnRH), also called hypothalamic blockers, drugs that belong to the group of hormonal therapies. When hormone therapy is discontinued, development resumes.

early menarche

When the first menses appear before the age of 10, it is called premature menarche.

Early onset of menarche has been observed:

  • in girls surrounded by stressful family environments, in those in foster care and in those living with a stepfather or stepmother;
  • in girls growing up in urban environments rather than those raised in rural environments;
  • in adolescent girls from families of high socioeconomic status more than in girls from families of lower socioeconomic status;
  • in girls who consumed more animal protein and less plant protein between the ages of three and five;
  • in girls who are overweight or obese

Late menarche

When the first menses appear between the ages of 16 and 18, it is called late menarche.

Primary amenorrhea is the term used to describe the absence of menarche in an adolescent female who has not had her first period by age 16 (secondary amenorrhea is the cessation of menstruation for three months or more after it begins) .

Late onset has been observed:

  • in adolescent girls with very low body mass due to hunger, malabsorption, or eating disorders such as anorexia nervosa;
  • in female athletes, suggesting that vigorous exercise of at least two hours a day delays puberty and, therefore, menarche;
  • in girls with abnormalities of the genitourinary tract;
  • In cases of absence of a normal uterus or vagina due to Müllerian agenesis, or Mayer-Rokitansky-Kuster-Hauser syndrome;
  • In case of complex hormonal abnormalities such as androgen insensitivity syndrome.

Organs involved

In addition to the female reproductive organs (ovaries, fallopian tubes, uterus and vagina), menarche is influenced by complex hormonal interactions involving the hypothalamus, pituitary gland and ovaries.

The adrenal glands, thyroid and pancreas also play a role: thyroid hormones are necessary for normal menstruation and their deficiency or excess can inhibit menarche.

An abnormal increase in insulin or adrenal androgens can affect normal ovarian estrogen production and decrease pituitary LH production.

The hormone leptin also appears to play a role in menarche.

Menarche, symptoms

Menarche tends to be painless and occurs without warning. However, ahead of your first period, you may notice the following symptoms:

  • cramps, pain, or tenderness in your belly, back, or legs;
  • belly bloating;
  • tender or sore breasts;
  • skin rash, acne/pimple flare;
  • mood swings;
  • fatigue and tiredness;

During your period, red or brown blood may appear on your underwear or in the toilet after using the bathroom. The bleeding might be light, so that you only see a few drops before the period ends, or it may start out light, get heavier, and then get light again before it ends.

Every woman experiences her period differently and the first periods are particularly unpredictable.

What could the parent do

Informing and preparing the girl for this event is a good idea.

The first period may or may not be a very delicate moment: every girl is different.

In any case it is advisable to create complicity, learn to listen to your daughter and accept that she is no longer a child.

How to handle it

If cramps are bothering you, the following remedies may help:

  • take a hot bath;
  • exercise and stretch;
  • place a heating pad or warm washcloth on your belly;
  • take medicines that contain ibuprofen (Brufen) or naproxen (Okitask).

Unless indicated by a doctor, the use of aspirin is not recommended, as it could cause Reye’s syndrome in people under 18 years of age .

How long does it last

If there is no fertilization, the endometrial tissue sheds and is eliminated with menstruation, which generally translates into 5 – 7 days of blood loss of varying extent.

When regularizing the cycle after the first period

The regularity of the cycle depends on many factors that must harmonize with each other. In general, menstrual cycle irregularities can be considered normal for about two years after menarche. Afterwards, an average of 28 days pass between one menstruation and the next, but this is a variable time that varies from woman to woman.

Growth after menarche

Growth does not stop with menarche.

As far as growth in terms of height is concerned, after menarche we see an average growth of a further 7 cm.

First cycle and menopause

According to an Australian study , compared to women who entered puberty at the ages of 12 and 13, women who had their first period at age 11 or earlier had an 80% increased risk of entering menopause before the age of 40, and the 30% increased risk of entering menopause between the ages of 40 and 44.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform,

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