Every woman’s body contains hundreds of different hormones, but there are a few that work together in complex ways to cause normal menstrual cycles. The menstrual cycle hormones include estrogen, progesterone, luteinizing hormone, follicle-stimulating hormone and gonadotropin-releasing hormone. Each of these has a different effect on the body and a specific role to play in the menstrual cycle.
The first of the menstrual cycle hormones to come into play is the gonadotropin-releasing hormone. It is released in the brain by the hypothalamus, and it starts a chain reaction for the rest of the menstrual cycle hormones. When gonadotropin-releasing hormone is released, it stimulates the production of follicle-stimulating hormone and luteinizing hormone in the pituitary gland.
During the menstrual cycle, follicle-stimulating hormone promotes follicle growth in the ovaries and the production of eggs. Luteinizing hormone works in conjunction with follicle-stimulating hormone to cause ovulation, which occurs when the egg is released from the ovary. The levels of follicle-stimulating hormone and luteinizing hormone rise and fall together throughout the course of the menstrual cycle. Another function of these two hormones is to cause the ovaries to produce estrogen and progesterone. Estrogen and progesterone then work together to prepare the body for possible fertilization of the egg.
The menstrual cycle can be divided into three distinct phases, with the first phase beginning on the first day of menstruation. During the follicular phase, decreasing levels of estrogen and progesterone cause the uterine lining to break down and exit the uterus in the form of menstrual blood. As this occurs, the follicle-stimulating hormone causes development of ovarian follicles, one of which continues to grow and produce estrogen. This follicle contains an egg.
During the ovulatory phase, luteinizing and follicle-stimulating hormones continue to increase and cause the follicle to release the egg. This is ovulation. During this time, estrogen and progesterone levels peak.
At the luteal phase, luteinizing and follicle-stimulating hormone levels both decrease. Progesterone and estrogen work in conjunction to thicken the uterus lining, in case the egg is fertilized. If the egg is not fertilized during the cycle, progesterone and estrogen levels decrease, which causes the uterine lining to break down, and menstruation starts once again.
A menstrual cycle consists of a complex series of physiological changes in a woman’s body. The five major menstrual cycle hormones play a crucial role in causing these changes. All of the hormones function together to allow this process to continue correctly and ensure reproductive health.
