In the reproductive system it produces a series of changes designed to prepare fertilization. Hormonal variations observed during the cycle are responsible for these changes as well as the possible pregnancy. Some of the body parts involved in the menstrual cycle are the brain, the pituitary gland, uterus and cervix, ovaries, fallopian tubes, and vagina. Some body chemicals called hormones rise and fall during the month level, and cause the menstrual cycle. The ovaries produce two important female hormones estrogen and progesterone. Other hormones involved in the menstrual cycle include follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by the pituitary gland.

Menstruation is part of the menstrual cycle, which helps the woman’s body every month prepare for a possible pregnancy. The cycle begins on the first day of the period. The average menstrual cycle lasts 28 days, however, a cycle can last from 23 to 35 days. During the first half of the menstrual cycle, estrogen levels rise and make the

Lining of the uterus grow and thicken. As a result of follicle stimulating hormone, an egg begins to mature in one of the ovaries. Around day 14 of a 28 day cycle, an increase in luteinizing hormone causes the egg leaves the ovary. This is called ovulation.

During the second half of the menstrual cycle, the egg begins to move through the fallopian tube toward the uterus. Increase levels of progesterone, which helps to prepare the lining of the uterus for pregnancy. If a sperm fertilizes the egg, and it adheres to the wall of the uterus, the woman becomes pregnant. If the egg is not fertilized, it dissolves or is absorbed by the body. If pregnancy does not occur, levels of estrogen and progesterone decrease, and the thickened lining of the uterus is shed during the menstrual. Period

Anatomically and physiologically can be considered the female reproductive system consists of three basic elements. The hypothalamus, pituitary and ovaries. The dynamic interplay between these three bodies allows the frequency characteristic of normal female sexual cycle. Morphological and endocrine changes that occur in each female cycle and are the natural consequence of the reproductive capacity of the species.

The hypothalamus is a gland that is part of the brain, and is below the thalamus. Releases at least nine hormones that act as inhibitors or stimulants in the secretion of other hormones in the anterior pituitary, so one can say that works together with this. One of the most important functions of the hypothalamus is to make the link between the nervous system and the endocrinologist system through the pituitary gland. Often it considered the central core of the vegetative or autonomic nervous system, within the central nervous system. It is also responsible for performing functions soma to-vegetative integration. Regulates body homeostasis in conjunction with the pituitary gland through a negative feedback system (body temperature, hunger, thirst, fatigue, anger, and menstrual cycle).

Any anomaly that alters the normal functioning between the hypothalamus, pituitary and ovaries, ie between the system and endocrinologist nervous system, determine an alteration in hormonal secretion and in parallel a disorder in fertility.