In Short: Cervical fluid is secreted by the woman's body before ovulation to improve the sperms' chances for survival and reaching the ovum. Due to the timing of its secretion, it can be used to identify the onset of fertility. The complete absence of cervical fluid is a strong indicator of infertility.
Cervical fluid is an important sign in fertility awareness. The woman's body begins to secrete estrogen shortly after menstruation, which causes glands around the cervix to secrete cervical fluid. As ovulation approaches, the amount of estrogen builds, causing the body to secrete even more fluid. The increased levels of estrogen also make the cervical fluid stretchy and clear.
As the level of estrogen builds, another hormone, called lutein, is released. Lutein causes the ovaries to release the ovum. The estrogen levels decrease somewhat after ovulation, causing the cervical fluid to dry up. This drying up process normally starts on or just after the day of ovulation.
Cervical fluid has several purposes in the area of human reproduction. First, it performs a lubricating function during sexual relations. Secondly, but more importantly, it provides a friendly environment for the survival of sperm after sexual relations have taken place. Without this environment, sperm would live no longer than several hours and would be literally stopped dead in their tracks, unable to move, unable to fertilize the waiting ovum. In the presence of cervical fluid, sperm are provided with both nutrients and a conduit for movement and may live up to five days in such an environment. Therefore, in addition to providing a pathway to the ovum, cervical fluid widens the fertility window beyond the daylong life span of the average ovum and hours-long life span of the average sperm. Sexual relations taking place several days before ovulation may still result in conception due to the increased viability of the sperm in the presence of fertile-quality cervical fluid.
Cervical fluid is therefore a positive sign that fertility is increasing and may be used as such in fertility awareness. For pregnancy achievers, it provides an excellent pre-ovulation indicator, whereas temperature alone can only identify ovulation after the fact.Cervical fluid may be observed directly, in which case you might notice the following qualities:* Sticky - A less fertile-type of fluid, not very conducive to supporting either sperm motility or lifespan. This may correspond to a Sticky vaginal sensation, as well.* Creamy - A lotion-like type of fluid, which can support sperm for longer periods than the sticky-quality type. This may correspond to a Wet or Moist vaginal sensation.* Eggwhite - The most fertile quality cervical fluid, it is clear, stretchy, and slippery. This type of cervical fluid resembles raw eggwhite, hence the descriptive name. This may correspond to a Lubricative vaginal sensation.
For a detailed explanation of how to observe and tell the difference between the types of cervical fluid and vaginal sensations, please refer to Taking Charge of Your Fertility, page 85 (this page reference is from the revised edition, in the original edition, please refer to page 78).