Your Hormones are Driving Your Fertility Signs

Your Menstrual Cycle and Your Hormones

You may wonder why we are talking about your hormones and not just getting to the details of how to best identify, chart and interpret your fertility signs. While it is possible to chart without fully understanding the role of your hormones, understanding what triggers your fertility signs and what they mean will make the clues more meaningful. Seeing the role that hormones play will show you how each of your fertility signs is directly related to your hormonal changes and demystify the entire process.

Your fertility signs, whether they are those you observe yourself (your temperature, cervical fluid, cervical position), or those measured by devices (OPKs, fertility monitors, microscopes), are related to this hormonal process. Your hormones, while giving you clues about your fertility status via your fertility signs, are also responsible for triggering the responses needed to prepare your body for a possible pregnancy. The diagram below shows you how your hormone levels change in relation to your menstrual cycle.

Your menstrual cycle is driven by your hormones. Hormones are biochemical substances that are produced in one area of your body and carried in your bloodstream to send signals that trigger responses in another part of your body. The hormones that control your fertility signals are produced in your hypothalamus (in your brain); your anterior pituitary gland (also in your brain, located behind and attached to the hypothalamus); your ovaries; and your adrenal glands (located on top of your kidneys). A series of hormonal steps trigger the events of your menstrual cycle.

1. The first thing that happens, at the beginning of your menstrual cycle, is that the hypothalamus produces GnRH (gonadotropin-releasing hormone). The GnRH pulses through your bloodstream from the hypothalamus to the pituitary gland in spurts every 60-90 minutes from menstruation until ovulation. The GnRH signals the anterior pituitary gland to secrete FSH (Follicle Stimulating Hormone) and later LH (Luteinizing Hormone). This is what is going on when you have your period and in the days before ovulation.
   
2. The Follicle Stimulating Hormone (FSH) as its name suggests, stimulates the development and maturation of follicles in the ovaries. One of these follicles will become dominant and contains the egg that will be released at ovulation. The developing follicles begin to produce estrogen.
   
3. The estrogen released by the developing follicles, and later by the dominant follicle, causes the lining of the uterus, the endometrium, to grow and thicken in preparation of implantation of a fertilized egg.
   
4. By about the seventh day of your cycle on average (but this can vary widely) the dominant follicle takes over. The egg within the other follicles loses its nourishment and dies as do the follicular cells.
   
5. The dominant follicle produces a sharp rise in estrogen. (You can recognize this stage of your cycle by closely monitoring your cervical fluid). Estrogen is at its peak one to two days prior to ovulation.
   
6. This estrogen surge signals the release of LH (Luteinizing Hormone) which is what is measured by ovulation predictor kits (OPKs). LH goes through the bloodstream to the ovary where it causes the ovary to release enzymes that make a hole in the sac that is the dominant follicle. This causes the dominant follicle to rupture and release the egg into the Fallopian tube where it can be fertilized. This is ovulation. The LH surge is necessary for ovulation to occur. The LH surge (the highest concentration of LH) occurs 12-24 hours prior to ovulation but LH begins to rise about 36 hours before ovulation.
   
7. Estrogen drops dramatically after ovulation.
   
8. The dominant follicle, transformed by LH, becomes the corpus luteum after ovulation. This phase of your cycle after ovulation is called the luteal phase since hormone production is governed by the corpus luteum. The corpus luteum continues to produce some estrogen, but now also produces progesterone which is the hormone that dominates this phase of your cycle. Progesterone, like estrogen, is needed to develop the endometrium so that a fertilized egg can implant and be nourished should fertilization occur. Your BBT (Basal Body Temperature) rises as a result of progesterone.
   
9. If an egg is fertilized, the corpus luteum's life is extended by the presence of the pregnancy hormone (hcG) and it keeps on producing progesterone and some estrogen and the development of the endometrium continues. As the pregnancy progresses, hormone production is taken over by the placenta.
   
10. If there is no pregnancy, the corpus luteum dies, progesterone levels fall and a new cycle begins.

Table Of Contents
(Important: See Table Of Contents for Copyright and Disclaimer)