Hormones work to instigate and control every process of the menstrual cycle, as stated by WebMD. This includes the hormones FSH, estrogen, LH and progesterone, which each serving a specific purpose in facilitating the menstruation process.
The follicle-stimulating hormone is produced by the pituitary gland and helps to develop an egg in one follicle of one ovary. Once this happens, the ovary begins to produce the hormone estrogen, which helps instigate the rebuilding of the uterus's lining, which broke down during the previous menstruation cycle.
The pituitary also produces the luteinizing hormone to instigate ovulation in the woman's body, which involves the release of the egg and the production of progesterone in the now empty follicle, according to First Response. This production of progesterone also increases the building of the lining of the uterus, allowing it to get thicker in preparation of the fertilized egg.
When the woman does not engage in intercourse or other means of reproduction, the unfertilized egg causes the production of estrogen and progesterone to halt. This halt in hormone production causes the lining of the uterus to break down and be released through the process of menstruation. In the event that the egg is fertilized by a male sperm, the fertilized egg will attach itself to the uterine lining and develop into a fetus.