Cervical mucus (CM) is not only a perfectly normal substance produced by your cervix, it also can help you determine when you are fertile or not. This vital fluid is made up of water, sugars, electrolytes, and proteins and is a key part of getting pregnancy (1). Long story short, CM determines whether sperm will be able to survive and travel to the ovum to fertilize an egg (2; 3)
CM Supports Sperm in 3 Vital Ways
2) Nourishment. Through the cervix to reach the egg in the fallopian tube is a long way to swim. The sperm need food along the way as well, and fertile CM provides the much-needed nutrition.
3) An easy substance in which to swim. While infertile CM, at a microscopic level, is like brambles and weeds that trip up the hopeful sperm, fertile CM has a beautiful crystalline structure that provides perfectly-shaped passageways to allow sperm to swim with the least effort, and in the right direction, to meet the egg on time for their important date. Fertile CM also helps filter out irregular sperm so only the most suitable bachelors arrive at the egg’s doorstep.
CM Changes With Fertility
CM generally follows the same predictable pattern each menstrual cycle. It goes like this:
Menstruation: Bleeding for around 3 to 7 days. This varies from woman to woman. During this time there may or may not be CM present.
None: After your period ends most women have a few days where there’s not a lot going on down there.
Sticky: Around day 7 or so, your cervix will start producing a sticky or pasty kind of CM. It may look like grade-school paste, or be slightly springy, but it’s mostly a solid kind of substance, not really a fluid so much. This type of CM means is that the period of fertility has begun since sperm might now be able to survive in the infertile CM long enough for the fertile CM to be produced, and in the fertile CM they can live for up to five days.
Creamy: As your cycle progresses, your estrogen level is rising every day, and with that rising tide of estrogen, the water content of your CM will increase. So essentially, take that pasty CM from yesterday, add some more water to it, and you’ve got Creamy CM!
Eggwhite: Eggwhite CM is called that because it resembles raw eggwhite. It’s clear, and slippery, and can usually stretch an inch or more between a finger and thumb. THIS is the really fertile stuff! It’s alkaline, and has a beautiful crystalline structure when viewed under a microscope. This special fluid can keep sperm alive for up to 5 days inside your body (4).
Watery: Sometimes the water content of a woman’s CM will be so high that the eggwhite CM is more like water, it’s clear, slippery, and doesn’t hold its shape at all. You will know it’s there by the very wet sensation in your vagina. You may even feel like you’ve started your period. This can be confusing but these “water gushes” just means very fertile CM.
And that takes us up to ovulation, at which point the egg has been released by the ovary and now we are back to a dry or sticky holding pattern until menstruation begins. (Note: Some women will experience a watery CM the day before their period, as the endometrial lining starts to break up.)
How to identify your fertile window:
To identify your fertile window, pay attention to your CM characteristics, like volume and consistency, at any time of day. Some women find that the easiest time to check is when they go to the bathroom. Before urinating, swipe a clean finger or a square of toilet paper at the opening of your vagina to collect CM, which will sit on top of the toilet paper, if you use it. Look at how much is there; you may have so much that it’ll feel like you’ve gotten your period or it will get onto your underwear.
Next, examine its texture and consistency by rubbing the mucus between two fingers. CM is usually categorized as none/dry, sticky, creamy, eggwhite, and watery. CM usually increases in water content until you ovulate, after which it will dry out.
Every body is different, so some people may produce all these types and some may skip from sticky to eggwhite, or some may never see the watery type. An important part of this process is understanding your own body and what is most fertile for you.
If you want more descriptions, check out this post.
Identifying Peak Day is also important when trying to conceive. Peak Day is the last day that you have fertile CM before less fertile mucus shows up. In terms of identifying Peak Day, volume doesn’t matter. For example, if you have one day with lots of eggwhite CM, then the next day you only have a little eggwhite CM, then the next day you have sticky mucus, the day with little eggwhite CM is considered the Peak Day. If you observe more than one type of CM, record all types or if you can only record one type, record the most fertile type, even if you only saw it once or if it was just a little.
Now you know that it’s produced by your cervix, it helps sperm live long enough inside your vagina to reach the egg, and goes through a predictable pattern each cycle, getting wetter as you approach ovulation, and drying up after the egg is released.
It may seem confusing at first, but continue to check your CM every day, and you’ll soon be able to distinguish your own unique CM patterns. Doing so can provide a great window into the state of your fertility.
Katz, David. (1991). Human cervical mucus: research update. Am J Obstet Gynecol. 1991 Dec;165(6 Pt 2):1984-6.
Bigelow, Jamie. (2004). Mucus observations in the fertile window: a better predictor of conception than timing of intercourse. Human Reproduction, Volume 19, Issue 4, April 2004, Pages 889–892,https://doi.org/10.1093/humrep/deh173