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The Mucus Chronicles

It all comes down to mucus. Life. Health. Conception. Contraception…the absence and presence of mucus determines it all.

That’s a heavy statement, I know. But if I could discuss just one topic with anyone curious about their reproductive health and fertility, it would be about mucus. And the most remarkable thing about this, is that many of us were not taught anything about mucus in our sex ed classes. Trust me, I got my Bachelor’s degree in Health Education and there was absolutely no talk of this cyclical “white flow”. It’s a parameter of the menstrual cycle that (optimally) shows up just as frequently as our period, but no one talks about.

So what exactly is cervical mucus and how do we know if we have it?

Cervical mucus is a hydrogel produced by glands in the cervical crypts. (The cervical whattt?) The cervical crypts are ciliated branch-like structures that line the inside of the endocervical canal, which connects the vagina (at the external os) to the uterus (at the internal os). Technically, the cervix is the narrow bottom section of the uterus. The cervical crypts are lined with mucus-producing cells and receptors for both estrogen and progesterone, which are the dominant reproductive hormones. As the follicles (sacks surrounding the immature egg cells) begin to grow at the start of the menstrual cycle, they produce estrogen. As those estrogen levels rise, the cervical crypts begin to produce E-type mucus, or estrogenic mucus. After ovulation, as estrogen levels drop a bit and progesterone levels increase rapidly, the cervical crypts create G-type mucus, or gestagenic mucus.

The estrogenic E-Type mucus is a catch-all term for the various types of estrogenic mucus, including L, S and P-type mucus. Each of these types of mucus have a specific role to play in our fertility. L-mucus is produced at the beginning of the pre-ovulatory follicular phase. It is alkaline (more on that in a moment), helps to dislodge the G-type mucus plug at the beginning of the fertile window, creates a supportive structure for S-mucus to form, filters out defective sperm, and closes the S-crypt openings once they contain several sperm (more on that later). L-mucus on its own is pasty or sticky and can be somewhat elastic, allowing it to stretch just a tiny bit (maybe ¼-¾ of an inch or less). It is often more opaque, but can also be somewhat translucent. S-mucus is secreted from the upper portion of the cervical crypts and is a more fluid-like consistency that tends to be translucent.

S-mucus, when combined with L-mucus, creates hallway like structures within the mucus that helps to activate and guide sperm transport. When you look at estrogenic mucus under a microscope, there seem to be clear channels for the sperm to move through.

The final category of estrogenic mucus is P-type mucus. This mucus has two purposes. It helps to facilitate L-mucus in liquifying the G-type mucus plug at the beginning of the fertile window (opening up the cervix) and it facilitates sperm transport from the cervical crypts towards the uterus and fallopian tubes for potential fertilization in an upward motion at the end of the fertile window. P-mucus is more watery, so when there is a higher ratio of P-mucus, it will feel lubricative when you wipe or touch the mucus, but it will be less viscous and you won’t be able to pick it up off the toilet paper or stretch it between your fingers…it will just look kind of wet on the toilet paper.

All mucus that we can see and feel is fertile.

Let me repeat this. ALL MUCUS IS FERTILE. Now, some Fertility Awareness Methods (like the Justisse Method) categorize the mucus into "Non-Peak" and "Peak" type mucus. However, all cervical mucus is fertile. The Non-Peak and Peak categories just differentiate how estrogenic (or close to ovulation) it might be.

Non-Peak mucus is any mucus that feels dry or smooth when you wipe, is creamy, yellow or white in color, and stretches less than 1 inch.

Peak mucus is any mucus that either feels lubricative when you wipe, has some type of translucent or totally clear color, OR stretches an inch or more.

Sperm can live in both Non-Peak and Peak-type mucus. So if you can feel something slippery when you wipe, or you can see something on the toilet paper (and certainly if you can pick something up off of it), sperm can live there and you’re fertile!

Now, let’s get back to the whole sperm survival and transport thing. Cervical mucus is the medium of life. With the exception of artificial reproductive technologies (ARTs), cervical mucus is the only reason that sperm and eggs ever meet. Generally speaking, the vagina is a fairly acidic environment. And this is great, because we don’t want bacteria living in there. However, sperm are relatively fragile cells that need to be within an alkaline environment to survive.

So the body creates alkaline cervical mucus to temporarily change the pH of the vagina and make it more hospitable for sperm. The mucus also contains sugars and proteins that helps to fuel the mitochondria of the sperm and allow it to live for a few days. When sperm are in contact with E-type mucus they are able to survive within the cervical crypts, uterus and fallopian tubes for about 3-5 days.

We expect people to have mucus present for anywhere from 2-7 days within their cycle. The days that they see this mucus are considered their fertile window. Prior to the beginning of the fertile window (as estrogen levels are still relatively low), and after ovulation (when progesterone is the dominant hormone) G-type mucus creates a mucus plug, which closes up the cervix. What this feels like externally, is a dry sensation when someone wipes before or after going to the bathroom.

When we look at G-type mucus under a microscope it has a web-like structure that makes it impossible for the sperm to penetrate. It’s also more acidic, so the sperm die within minutes of coming into contact with it.

The combination of the cervix opening and closing (in relation to the type of mucus present), and the change in pH (due to E-type and G-type mucus) determines when in the reproductive cycle any sperm will survive and have the chance to fertilize an egg. Being able to accurately observe and identify cervical mucus is what allows an individual (or couple) to determine the exact days that they’re fertile in real time.

It’s important to recognize that our fertile days can change from one cycle to the next. Because of this, we need to be checking for mucus every day, especially when we go to the bathroom (we’re already wiping, so we might as well get the low-down on our fluctuating fertility). Relying on apps that predict your fertile window based on cycle length is just a technological rhythm method. Checking for mucus in real time gives you accurate and individualized information.

Now it’s important to note that cervical mucus is not the only fluid or discharge we might experience throughout the month. Our vulvas sweat, so we might notice a dampness on the toilet paper or on our underwear. When the cervix changes position (either before or after menstruation or before or after your fertile window) it can release a watery substance, which we can sometimes feel as we go about our day. (Anyone else swear they’ve gotten their period, only to see nothing on the toilet paper when they run to the bathroom?!) Our vaginas are also constantly cleansing themselves and replenishing old cells. Vaginal cell slough is a super common observation that you might see at any point throughout the cycle. It can either look like a shiny or iridescent spot on the toilet paper when you wipe (the trick is to touch that shiny spot and if it goes away, it’s just cell slough), or it might look like dried white flakes on your underwear at the end of the day. And last, but not least, a couple of the more confusing fluids we might notice can be arousal fluid and semen. While arousal fluid can feel lubricative initially, it also evaporates fairly quickly, so when you rub it between your fingers the lubrication will dissolve swiftly, as opposed to lubricative cervical mucus. Semen also tends to have a slightly different color and texture than cervical mucus, as well as a different scent. It tends to be more whitish-yellow or whitish-gray in color, doesn’t often stretch between the fingers more than once (if at all), and it has a more musky scent.

Remember how I mentioned that cervical mucus is a hydrogel? There’s a trick you can use with water to help determine what is cervical mucus and what might be arousal fluid or semen. When cervical mucus comes in contact with water it will generally maintain its structure for a bit, while arousal fluid and semen will dissolve rather quickly. Another trick to help differentiate semen from cervical mucus is to use what’s called the Semen Elimination Technique (SET). To use the SET, you’ll want to go to the bathroom within an hour after intercourse. While you pee, you’ll want to do a series of kegel exercises, wiping between each one. As the pelvic floor contracts and relaxes, it will push out any excess seminal fluid. Once you’ve wiped it away a few times, there will be less (or perhaps none) to leak out later on in the day, which can sometimes cause confusion. >> It’s also important to note that if sperm transfer were to occur (i.e. if any sperm and mucus meet), it would happen within the first 1.5-2 minutes after ejaculation, so doing the SET will not impact the chance of pregnancy. In fact, the majority of the sperm will not transfer, and it will either be absorbed/cleared by the vagina or it will seep out later on.

In general, we expect people to have cervical mucus for anywhere between 2-7 days (3-6 is considered optimal). There are, however, certain physiological conditions that may impact how responsive the cervix is to various hormone changes, which can alter whether or not someone experiences mucus. For example, when we’re:

  • coming off of hormonal contraceptives

  • experiencing hormonal imbalances

  • have just begun getting our menstrual cycle

  • entering into perimenopause

  • postpartum or nursing

  • have cervical dysplasia

Any of these scenarios can impact our mucus patterns and they may look different than the expected parameters. Atypical mucus patterns can make it very challenging to assess our fertility, both for contraceptive purposes and when we’re trying to conceive. If any of the above scenarios describe where you are in your reproductive life span or what you’re currently experiencing, it is best to work with a trained Fertility Awareness Educator as you’re learning to assess your menstrual cycle parameters.

And while it can be initially somewhat confusing to differentiate the various types of mucus and vaginal fluids, acquiring the skill of Fertility Awareness and body literacy is absolutely revolutionary. You owe it to yourself, those who came before you, and those who might learn from you in the future to get acquainted with that “white flow”…the elixir of life!

Curious about cervical mucus or your unique menstrual cycle parameters? Check out my FREE guide to assessing your menstrual cycle parameters or contact me to schedule an initial consult to discuss your reproductive health goals!

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