Menstruation period may vary from one woman to another, it all depends on the body conditions and also can be hereditary. However, periods do occur once in a month. Though regular period is preferable but in rare cases there are women who have irregular periods and they have successfully adjusted to it.

The menstrual period normally lasts for two to seven days but generally three to five days is more common. The menstruation cycle is generally 28 days long but depending on the age and body conditioning it may vary from 23 days to 35 days. Once the period has occurred there is a gap of about three weeks till the next period occurs.

The age of menstruation varies from 8 years to 16 years in females but generally the age 12 is considered to be the average menstruation age. Menstrual cycle also varies from girls to girls; some girls may have 28 days menstrual cycle, some may have 30 days menstrual cycle while others may have 35 day cycle. The body requires time to adjust itself to the changes which are taking place; this is one of the major reasons why during the initial years of menstruation, irregular menstrual period becomes a norm.

So a girl may have 30 day cycle for two months and then the next month she may have a 28 day cycle. However in due course of time the menstrual period becomes regular while in some rare cases the irregularity may continue. But the body adjusts itself to this uniqueness. The period may continue up to the age of menopause which is generally 51.
In many cases during period physical and emotional reactions such as tiredness, irritability, depression, mood swings, headaches, menstrual or abdominal pain occurs.

If period is irregular or if during the period you experience intense physical or emotional changes in yourself; then you should opt for proper medical advice.