Why does menstruation occur?

Menstruation, also known as a menstrual period, is a normal physiological process that occurs in the female reproductive system. It is the shedding of the uterine lining (endometrium) and its expulsion from the body through the vagina. Menstruation occurs as part of the menstrual cycle, which is orchestrated by hormonal changes, and it serves several important functions in the female reproductive system:

1. Preparation for Pregnancy: The primary function of menstruation is to prepare the uterus for a potential pregnancy. During the first half of the menstrual cycle, the endometrium thickens and becomes more vascularized in response to rising levels of estrogen. This thickened lining provides an ideal environment for the implantation and nourishment of a fertilized egg.

2. Egg Discharge: Menstruation typically marks the end of the menstrual cycle, which begins with the release of an egg (ovulation). If fertilization of the egg does not occur, the corpus luteum, a temporary endocrine structure formed in the ovary after ovulation, regresses, leading to a decrease in the levels of estrogen and progesterone. This hormonal drop triggers the shedding of the uterine lining.

3. Removal of Old or Unneeded Tissue: Menstruation helps remove the old, damaged, or unneeded tissue from the uterine lining, ensuring that the uterus maintains a healthy environment for potential future pregnancies. This also eliminates any remnants of a non-viable pregnancy, which is a natural part of the body’s quality control mechanism.

4. Regulation of Hormonal Cycles: The menstrual cycle is regulated by a complex interplay of hormones, including estrogen and progesterone. Menstruation is a visible indicator of the cyclical hormonal changes within the body. It allows for the preparation of the uterine lining in anticipation of pregnancy, and if pregnancy does not occur, it triggers the start of a new cycle.

5. Purge of Bacteria and Pathogens: Menstruation can also help eliminate bacteria and pathogens that may have entered the female reproductive tract. The menstrual flow carries these potential invaders out of the body, reducing the risk of infection.

It’s important to note that while menstruation serves these functions, not all individuals who experience menstruation intend to become pregnant. Menstruation is part of the reproductive system’s cyclical process, and it occurs regularly, roughly once a month, in most menstruating individuals of reproductive age.