Menstruation is a monthly cycle that occurs in girls and starts at puberty – typically between the ages of 8 and 16 and continue until menopause at about age 45-55. It lasts for about 3 to 6 days and is the regular discharge of blood and tissue from the inner lining of the uterus through the vagina. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women.

The menstrual cycle is a hormonal driven cycle; day 1 is the first day of the period while day 14 is the approximate day of ovulation and if an egg is not fertilized the cycle begins again. It is unquestionably, a crucial event in the lives of women.

Using the word ‘period’ is a misnomer, as they vary and when the start, it may take a few weeks before there is a degree of regularity. Also the flow may vary from scanty to moderate to heavy. Most women would be very surprised to learn that the total fluid discharged over one period averages at 2 ½ table spoons!

Problems associated with menstruation include pain (with cramps), food cravings, headache, fatigue, heavy bleeding, skipped periods and mood swings.

Regardless of this, the menstrual cycle provides important body chemicals, called hormones, to keep the body healthy. Women feel refreshed after a normal period.

https://en.wikipedia.org/wiki/Menstruation

https://medlineplus.gov/menstruation.html#summary

https://www.medicalnewstoday.com/articles/154699.php