At the heart of the menstrual cycle are a handful of hormones, or substances within the body, that are responsible for causing the physical changes that we associate with the cycle.^{8, p. 160} These changes include ovulation, menstruation (your period), and the symptoms related to your cycle that some women can experience to different degrees. These hormones include:

• Gonadotropin-releasing hormone (GnRH) – produced by the hypothalamus (a part of the brain)^{7. Dorland’s Med. Dictionary, p. 899} and stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland.^{31. Parker, p. 18; 21. Silberstein p 149 ABC}
  
  
• Follicle-stimulating hormone (FSH) – produced by the pituitary gland and stimulates the growth of follicles in the ovaries, which secrete estrogen. ^{24. Van Wynesberghe, p. 959}
  
  
• Luteinizing hormone (LH) – produced by the pituitary gland and works with FSH to cause ovulation and later, the release of estrogen and progesterone. ^{10. Berek, 169; 17. Rebar 1498A,B}
  
  
• Estrogen – hormone secreted by ovarian follicles and the corpus luteum that stimulates thickening of the uterine wall, maturation of an egg, and development of female sex characteristics. Also provides feedback to inhibit FSH secretion and increase LH secretion. ^{24. Van Wynesberghe, p. 959}
  
  
• Progesterone – hormone secreted by the corpus luteum that stimulates thickening of the uterine wall and formation of mammary ducts. ^{24. Van Wynesberghe, p. 959}

Learn more about the symptoms related to your cycle.