How the menstrual cycle is calculated?

How the menstrual cycle is calculated?

The first period or menstruation occurs at puberty, around 11-13 years of age, marking the beginning of the menstrual cycle for young women.

The start of menstruation comes from the destruction of the inner layer of the uterus, called the "uterine lining" or "endometrium".

Each cycle begins on the first day of your period and ends the day before your next period.

For most women, menstruation occurs in a relatively regular and predictable cycle on average every 28 days and usually lasts 3 to 5 days. It is during this 3-5 day period that women may experience discomfort characterized by stomach aches, cramps, excessive fatigue, mood swings, headaches or nausea.

The length of the cycle can nevertheless be characterized as long if longer than 35 days or short if shorter than 21 days.