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Menarche is the first menstrual period a female experiences. It is the final event of a specific series of physiological events that occur during puberty. Growing taller and broader,developing breasts, and the appearance of pubic hair are a few of those changes.

Menarche is a very complex phenomenon controlled by a multitude of mechanisms, including factors not fully understood by scientists at the moment.

Since menarche depends on so many different physical, hormonal and genetic factors, the age at which girls start menstruating varies greatly.

Certain conditions cause menarche to be delayed or early.

Physiology of menstruation

The menstrual cycle is controlled by the hypothalamus-pituitary-ovary hormonal axis. The hypothalamus and pituitary are parts of the brain.

The hypothalamus starts secreting GnRH (gonadotropin releasing hormone) at menarche. This hormone triggers the secretion of FSH (follicle-stimulating hormone) and LH (luteinizing hormone).

These two hormones are responsible for the selection, development and maturation of egg follicles in time for ovulation. The developing follicle secretes estrogen. Estrogen leads to the proliferation and development of the endometrium. Following ovulation, the corpus luteum secretes progesterone.

If a woman does not get pregnant, menstruation occurs and endometrial tissue, blood and clots are expelled through the vagina.

Control of menstruation

Neurologists believe that the cerebral cortex has a role in determining the timing of menarche.

The fact that psychological stress affects the timing suggests this. Thus, a girl who is undernourished or in a turbulent family may attain menarche very late.

A high body mass index in childhood, a low birth weight, being the only child in the family, the mother having had pre-eclampsia, being exposed to smoking and not breastfed are directly related to an early menarche.

Disorders of menarche

The age at which puberty starts also varies considerably. The average age range is between 12-16 years. But some girls may start menstruating either earlier on later than this due to a whole host of reasons.
In families with a history of early or late menarche, kids also tend to follow the parental trend.

Precocious puberty is a rare condition where all the events of puberty occur at an unusually early age. Hypothalamic lesions, McCune Albright syndrome, hormone secreting tumors and administration of hormones as treatment for other conditions may cause precocious puberty.

Early menarche can lead to some complications. Because women are exposed to high levels of estrogen for a longer period if they started menstruating earlier, the risk of breast cancer and cervical cancer is higher in this group of individuals.

Primary amenorrhea

Puberty may be delayed due to under-nutrition, hypopituitarism, systemic diseases, brain lesions and other factors.

The absence of menstruation is called amenorrhea. Primary amenorrhea is when menstruation never occurred.

Primary amenorrhea may be due to anatomical causes like trans-vaginal septum or an abnormal uterus and hormonal cause like hypopituitarism. Secondary amenorrhea may be due to hormonal disturbances, drugs, and severe medical or psychological illnesses.

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