91Ó°ÊÓ

Menstruation, commonly referred to as the menstrual cycle, is a natural process that occurs in women of reproductive age (sexual maturity). The menstrual cycle is a hormonal process that occurs each month to prepare a woman's reproductive system for the possibility of pregnancy. The menstrual cycle lasts between 21 to 35 days and is controlled by the rise and fall of hormone levels.

Menstruation typically occurs when a woman's body is not pregnant and must shed the lining of the uterus. This shedding process happens due to hormonal changes, specifically the decrease in levels of estrogen and progesterone. These hormonal changes cause the uterine lining, called the endometrium, to break down and be expelled from the body through the vagina. The process is the body's way of maintaining a healthy environment for a potential embryo to develop and implant, should fertilization occur.

There are several conditions under which menstruation might not occur, including: 1. Pregnancy: Menstruation typically stops during pregnancy, as the hormonal changes required to maintain the fetus prevent the monthly shedding of the endometrium. 2. Menopause: Menstruation eventually stops altogether when a woman reaches menopause, which marks the end of a woman's reproductive years. This is due to a decrease in estrogen and progesterone levels, causing the endometrium to stop building up and not requiring shedding. 3. Hormonal imbalances: Conditions like polycystic ovary syndrome (PCOS) or thyroid issues can cause hormonal imbalances, leading to irregular or absent menstruation. 4. Stress: High levels of stress can disrupt hormone levels, resulting in irregular or missed periods. 5. Excessive exercise or malnutrition: Intense physical activity or extreme weight loss due to poor nutrition can lead to hormone imbalances and, therefore, missed or irregular menstrual cycles. 6. Birth control: Some hormonal birth control methods, like contraceptive pills, patches, or injections, can cause temporary cessation of menstruation as they affect hormone levels and prevent the uterine lining from thickening and shedding.

Menstruation is a natural process that occurs in women of reproductive age due to hormonal fluctuations that lead to the shedding of the uterine lining when pregnancy does not occur. Conditions that can lead to menstruation not occurring include pregnancy, menopause, hormonal imbalances, stress, extreme exercise or malnutrition, and the use of hormonal birth control.