What is the menstrual cycle? How to calculate it?
A menstrual cycle is a regular change that occurs in the female body under the influence of hormones. The average length of the menstrual cycle is 28 days, but the normal cycles are considered to be between 21 and 35 days. The first day of the cycle is the first day of menstrual bleeding. The last day of the cycle is the day before the next menstrual period occurs.
The menstrual cycle is divided into 4 phases:
1. Menstruation - menstrual bleeding (decrease in the activity of hormones),
2. The follicular phase - oocyte maturation phase (increase in estrogen concentration - Graaf's follicle matures under the influence of hormones)
3. Ovulation - the estrogen level reaches its highest concentration - a rupture of the follicle occurs, from which an egg cell is released
4. The luteal phase - its length is usually constant and usually lasts from 10 to 16 days - during this phase the level of progesterone increases, the mucous tissue grows, which prepares itself to accept the embryo.