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Cervical Mucus and Fertility

Cervical mucus and fertility play a fundamental role in the TTC process by nourishing and protecting sperm as it makes the long, arduous journey through the female reproductive tract to meet the egg. So, as you become more familiar with your cervical mucus, you will be able to better time having sex in order to conceive.⁠

In simple terms, cervical mucus is a fluid secreted by the cervix, the production of which is stimulated by the hormone estrogen. Throughout your menstrual cycle, the amount and quality of cervical mucus that is produced will fluctuate, and by observing these changes you can begin to predict the most fertile days in your cycle.⁠ That being said, “should” be able to detect cervical mucus changes however, according to the Mayo Clinic, 23 out of 100 women practicing the cervical mucus method to prevent pregnancy in the first year of use, will actually get pregnant. What that says to me is that a lot of women have trouble detecting this exact physiological change- so if you don’t detect it, don’t worry! 

As you approach ovulation, estrogen levels begin to surge, which causes the cervix to secrete more cervical mucus that is of a so-called “fertile quality”. This fertile-quality cervical mucus, also known as egg white cervical mucus (EWCM), is clear and stretchy, similar to the consistency of egg whites, and is the perfect protective medium for sperm in terms of texture and pH.⁠

Having enough egg white cervical mucus during your fertile window will actually improve your chances of conceiving. And, by noticing when your body is producing egg white cervical mucus, you will be able to identify your most fertile days.⁠

Cervical mucus plays and Fertility an important role in selecting motile, mostly morphologically normal sperm for fertilization. Insufficient production of fertile-quality cervical mucus or the presence of hostile cervical mucus may result from a variety of factors including diet, stress, hormonal issues, or even from taking prescription medications like Clomid.⁠

The in vitro sperm–mucus penetration test (SMPT) is a sperm function test which measures the ability of sperm in the semen to swim up into a column of cervical mucus or substitute. 

Normally, this cervical mucus is thick and impenetrable to sperm until just before release of an egg (ovulation). Then, just before ovulation, the mucus becomes clear and elastic (because the level of the hormone estrogen increases). As a result, sperm can move through the mucus into the uterus to the fallopian tubes, where fertilization can take place.

Abnormal mucus may do the following:

-Not change at ovulation (usually because of an infection), making pregnancy unlikely

-Allow bacteria in the vagina, usually those that cause infection in the cervix (cervicitis), to enter the uterus, sometimes resulting in the destruction of sperm

-Contain antibodies to sperm, which kill sperm before they can reach the egg (a rare problem)

However, problems with cervical mucus rarely impair fertility significantly, except in women who have chronic cervicitis or a cervix that has been narrowed (called cervical stenosis) by treatment for a precancerous abnormality of the cervix (cervical dysplasia).