Why does menstruation occur?

Menstruation is the shedding of the uterine lining, which occurs as a result of a complex interplay of hormones in a woman's body. The main hormonal drivers of the menstrual cycle are estrogen and progesterone, which are produced by the ovaries. The menstrual cycle is controlled by the hypothalamus and the pituitary gland, which release hormones that regulate the ovaries.

Here's an overview of the process:

Ovulation: The menstrual cycle begins with ovulation, which is the release of an egg from the ovary. This occurs approximately 14 days before the start of the next menstrual period.

Hormonal changes: After ovulation, the ovary produces progesterone, which thickens the lining of the uterus to prepare for a possible pregnancy. If the egg is fertilized, the fertilized egg implants itself in the uterus, and pregnancy begins.

Menstruation: If the egg is not fertilized, the thickened lining of the uterus is not needed and is shed, along with some blood, during menstruation. Menstruation typically lasts 3-7 days and is accompanied by cramps and other symptoms such as bloating and headaches.

New Cycle: The end of menstruation marks the start of a new cycle, and the process begins again with the growth and thickening of the lining of the uterus in preparation for the next ovulation.

It's worth noting that there are many factors that can affect the menstrual cycle, including stress, poor nutrition, and certain medical conditions, and that some women may experience abnormal cycles or periods which can be due to hormonal imbalances or other health issues.