What Is Menarche?

Menarche is the result of many hormonal interactions, especially the hypothalamus-pituitary-gonad axis. This process combines with telarche to initiate puberty.
What Is Menarche?
Diego Pereira

Written and verified by el médico Diego Pereira.

Last update: 10 May, 2023

Menarche is the term used to talk about the first menstruation. It’s the result of a set of very complex hormonal changes that also result in the development of secondary sexual characteristics.

This doesn’t only imply a changing body, but also new social and family needs that, on some occasions, may not be easy to face. In addition, some girls could develop these signs early or late, with pathological causes.

Sociocultural perspective

The appearance of menstruation in women is a common event, but for millennia it has been considered taboo. This may be related to the little understanding of human physiology.

The loss of abundant blood through the genitals, which is repeated cyclically, often had supernatural connotations. Perhaps for this reason, in many current societies menstruation is still considered a restricted topic. Fortunately, in recent years there have been efforts to raise awareness about the issue.

The truth is that it’s a complex process and that it’s used as the best indicator of sexual maturation in women. It’s related to puberty and marks the onset of early adolescence.

Physiological changes leading to menarche

The first menstruation is the body’s response to a set of very important changes. The main protagonist in this process is the hypothalamic-pituitary-gonadal complex.

The hypothalamus is responsible for the secretion of releasing hormones. These travel to the pituitary and, in turn, stimulate the production and release of other substances, such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

They travel through the body to the gonads, which in the case of women are called ovaries. Finally, they produce hormones known as estrogens, vital for a woman’s sexual development.

These changes are very progressive and slow and, in fact, are considered the reactivation of the hypothalamic-pituitary-gonadal system. During the first months of life, it works to direct brain changes.

The first menstruation occurs long after the start of development in the breasts, which is why some people consider this last event as a predictive factor.

Young woman with menarche pain.
Menstrual pains can be more intense during the first menstruations.

Epidemiological aspects of menarche: when does it appear?

Menarche usually has different ages of onset. Since it’s the result of genetic and environmental interactions, national studies are usually carried out with some frequency to evaluate this aspect.

In Europe, with the improvement of socio-sanitary conditions after the first half of the 20th century, there has been a gradual decrease in the age of menarche. This is almost the same in all the countries of the region. The same happens in other populations that improve their general health situations over the years.

In a Spanish study published in 2008, it was found that the mean age of menarche in the evaluated participants was 12.42 ± 1.01 years. In fact, the age at which the mothers reported having had their first menstruation was very similar. The authors compared the results with some obtained in previous studies, evidencing a progressive decrease in age over time.

Of course, these are studies with acceptable methodologies, but they depend a lot on the quality of the sample used. This implies that the results could change over time.

Factors that can change the time of onset

The natural changes that influence the age of presentation of menarche are very varied. They may include social, economic, genetic and environmental factors.

The combination of these elements has a significant impact on the nutrition of girls, a decisive element when the first menstruation begins. The increase in adipose tissue (formed by fats or lipids) is related to the secretion of leptin, a hormone that can decrease the sensation of appetite.

But during puberty, leptin has another function: to stimulate the production of hormones by the hypothalamus. This favors the activation of the hypothalamic-pituitary-gonadal axis, with the consequent appearance of menarche.

Economic and social aspects influence these changes, as explained by a Chilean study. The researchers analyzed 1,302 cases of girls and grouped them according to socioeconomic status and body mass index. They found that the age at menarche was much lower in participants with a lower socioeconomic status and a higher body mass index.

What happens when menarche arrives before or after the average age?

The ages that have been mentioned up to now correspond to a population pattern from we can give expected age ranges. However, there are times when menstruation comes at a faster or slower rate.

This may be due to an exception to the rule, since not all bodies behave in the same way. However, it can also be the result of diseases with variable severity.

It should be noted that the terms early or late puberty don’t only refer to menarche. In fact, in girls one of the main indicators is the age of breast development or thelarche.

Early puberty

In general terms, it’s possible to classify this disorder into two types: of central and peripheral origin. The first are those with an underlying hormonal cause. There’s usually pathologic activation of the hypothalamic-pituitary-gonadal axis.

According to the Mayo Clinic, very rarely can this be the result of tumors in the central nervous system. Constant radiation exposure, structural alterations such as agenesis of the corpus callosum, and hypothyroidism could also cause this problem.

Conditions of peripheral origin only usually produce an increase in sex hormones. It happens in cases of congenital adrenal hyperplasia, ovarian cysts or tumors or in McCune-Albright syndrome.

Delayed puberty

In this case, the problems are usually due to inactivity of the hypothalamic-pituitary-gonadal axis. This either acts at a very slow rate or the concentration of hormones produced isn’t significant enough to create physical changes.

Of course, there are also underlying diseases that condition the appearance of the disorder. This leads to psycho-affective problems that are often the reason for consultation. This situation can lead to poor school performance, family problems, and difficulty making new friends.

Gynecological consultation.
The medical consultation in cases of normal menarches is to guide the parents, above all.

Differences between menarche and other menstruations

Due to the immaturity of the hormonal system during puberty, the first periods aren’t always the same as those in adult life. In fact, these tend to be quite irregular as a response to the body’s different adaptation mechanisms.

It could take up to two years for the changes to become regular. During this period, education plays a fundamental role in guaranteeing that the girl adapts well.

After the onset of menarche, the body is considered to be in the process of developing for reproductive function. From a social point of view, it can also represent an important change, since it’s the expected transition to adolescence.

Hormonal changes produce new needs. Interest in body image, the need for independence and wanting to establish different social relationships are the priorities at this time.

When to go to the doctor?

In theory, after the appearance and regularization of menstruation in girls it’s advisable to go to the pediatrician. They will guide, especially first-time parents, about the normal changes that will happen in a young woman’s life and how to deal with menstruation.

In cases of early or late puberty, it’s preferable to see a professional as soon as possible. As we mentioned, certain diseases manifest themselves in this way. If necessary, you may need to refer the girl to other specialists, such as the endocrinologist.

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