?Normal menstrual loss is about 25ml per day for 4-5 days per month. The amount of blood loss varies between individuals, but tends to get heavier with age.

?Menarche is the start of the first menstrual period. The average age of menarche is 13 years, but it can be as early as 8 years and as late as 18 years and still be normal.

Menstruation cycle

The menstrual cycle is a recurring cycle of physiologic changes that occurs in reproductive-age females. Overt menstruation (where there is blood flow from the vagina) occurs primarily in humans and close evolutionary relatives such as chimpanzees.[1] The females of other species of placental mammal have estrous cycles, in which the endometrium is completely reabsorbed by the animal (covert menstruation) at the end of its reproductive cycle. This article concentrates on the menstrual cycle as it occurs in human beings .The menstrual cycle is under the control of the hormone system and is necessary for reproduction.

Causes

Causes of primary amenorrhea:

?Delay may be normal if puberty characteristics, such as breat development, are present by age 13

?Birth defects of the female reproductive system

?Lack of an opening in the membrane at the entrance of the vagina (hymen)

?Problem with the hypothalamus gland

Causes of secondary amenorrhea:

* Pregnancy

* Stress and anxiety

* Drastic weight reduction

* Hormonal imbalance

Menstrual Symptoms

Many women experience some symptoms relating to the menstruation cycle. Menstruation symptoms may at any time from ovulation to the middle of their period of bleeding. These symptoms are known by the term, PMT or PMS, and are caused by hormonal changes. Some of these symptoms may include:

?Bloating;

?Mood swings;

?Depression;

?Feeling irritable;

Menstruation Products

There is a wide range of menstruation products that help people through their periods and throughout the entire menstruation cycle. Menstruation products can be divided into the following categories.

?Products that absorb the blood and other menstrual discharge. Two of the most popular methods for absorbing menstrual discharge are tampons and pads. You can also find natural menstruation absorbers, such as cloth pads.

?Products that help with PMT and other menstruation symptoms. This includes drugs that may be bought from a chemist, but also includes alternative menstruation products. There are many natural therapies and tablets that are designed specifically to help with symptoms caused by menstruation.

Treatment

?For amenorrhea caused by normal delay of menstruation onset, have patience until age 16. However, keep in mind that the delay is only normal if the girl displays some signs of puberty, such as breast development

?Consult your obstetrician to determine if you may be pregnant.