The menstrual cycle is a complex biological process that occurs in women of childbearing age. It lasts on average 28 days, but can vary from one woman to another and from one cycle to another.
The menstrual cycle is divided into four main phases:
1. The follicular phase (days 1 to 14)
During this phase, a follicle, containing an egg, develops in one of the ovaries. The level of the hormone estrogen increases, which stimulates the growth of the uterine lining.
2. Ovulation (day 14)
The mature follicle releases the egg into the fallopian tube. This is the time in the cycle when pregnancy can occur if the egg is fertilized by a sperm.
3. The luteal phase (days 15 to 28)
If the egg is not fertilized, it disintegrates. The level of progesterone, another hormone, decreases, leading to the breakdown of the uterine lining.
4. Menstruation (days 28 to 1)
The uterine lining and blood are evacuated through the vagina in the form of bleeding: these are the periods. Periods mark the start of a new menstrual cycle.
Hormones play a crucial role in the menstrual cycle.
- The pituitary gland, located in the brain, secretes hormones that stimulate the ovaries to produce estrogen and progesterone.
- The ovaries, in turn, release these hormones into the bloodstream, where they act on different organs of the body, including the uterus.
- The menstrual cycle can be influenced by various factors, such as stress, exercise, diet and certain medications.
It is important to note that the menstrual cycle is not always regular.
Many women have cycles that are shorter or longer than the average 28 days. Cycles can also be irregular, meaning the length of time between periods can vary from month to month.