When embarking on a fertility journey, there’s a lot of new lingo to learn. Acronyms abound (TTC, POAS, HPT, oh my!) and with them come a never-ending stream of terminology that hasn't seemed relevant since ninth-grade health class. It’s enough to make a person feel totally overwhelmed and out of place. 

Today, we’re here to tackle just one of those terms — cervical mucus — and break down exactly what it is and why it’s important for understanding your fertility. And rest assured that, unlike health class, there’s no pop quiz at the end. 

woman writing cervical mucus detail in a journal

What is cervical mucus, exactly?

Cervical mucus is pretty much what it sounds like: a liquid substance produced by your cervix, aka the muscular canal connecting your uterus and vagina. “It lubricates the cervix and vagina and also transports sperm from the vagina up through the cervix,” says Rachel Blake, MD, a Boston-based OB/GYN and fellow at the American College of Obstetricians and Gynecologists (ACOG).* The mucus gets mixed in with other fluids and bacteria in your vagina to make discharge (you know, the stuff that you see in your underwear every so often). 

What can cervical mucus tell me about my fertility? 

Your cervical mucus changes in volume, color, and texture throughout your menstrual cycle, says Dr. Blake. If you have a regular cycle, she says — meaning that you get your period consistently every 21 to 35 days, according to the ACOG — the changes in your cervical mucus can signal when you’re ovulating.

Some people track their mucus changes to help them time sex, either to get pregnant or to avoid it. This fertility planning technique is called the cervical mucus method, or the Billings Ovulation Method. According to the ACOG, cervical mucus tracking is a reliable way to detect ovulation on your own without any other tools, although it’s not 100 percent accurate. (More on why in a bit.)

Here’s a quick overview of how cervical mucus changes throughout a standard cycle

  • On your period: You likely won’t notice it much while you’re bleeding, says Dr. Blake; if you do, you may notice that your overall discharge is a little stickier. 

  • After your period: Once your period wraps up (around days seven to 10, Dr. Blake says), you’ll start to see mucus that’s a bit thicker and creamier in consistency. 

  • Leading up to ovulation: The exact timing depends on the length of your cycle, Dr. Blake says. But generally, your cervix will start to produce more mucus as your egg matures and prepares for ovulation. The mucus becomes “more liquidy, clearer, and a little thinner,” she says. 

  • Ovulation: Immediately before and during ovulation, your cervical mucus looks like raw egg whites, says Dr. Blake. It’s kind of stringy and you can actually stretch it between your two fingers — a sign of your “peak” fertility, she says. This corresponds with day 14 or 15 of an average 28-day cycle, she adds, but the specific date depends on your unique menstrual cycle. 

  • Post-ovulation: Once your ovaries release the egg, your cervix stops producing as much mucus. It’ll start to thicken up again, and become less noticeable before your period, says Dr. Blake.  

If you’re using this method to get pregnant, you’d want to have unprotected sex in the days leading up to and during ovulation—when your mucus gets increasingly slippery and stringy. If you’re using this method to prevent pregnancy, you’d want to avoid sex during that time (or use another kind of contraception, like condoms), as well as during your period. 

The amount or quality of your cervical mucus isn’t necessarily something you can outright control, since it’s influenced by your hormones. Staying hydrated may help since cervical mucus is mostly fluid (and if you’re dehydrated, it’s harder to make any fluids). There are also some supplements that aim to support the healthy production of fertile cervical mucus, like Fairhaven Health’s FertileCM Cervical Mucus Production ($22 for a one-month supply).* Visit Fairhavenhealth.com to get 15% off! 

woman pouring glass of water

Are there any downsides or limitations to cervical mucus tracking? 

Cervical mucus tracking can be a helpful tool in trying to understand when you’re ovulating, but it comes with lots of caveats, says Dr. Blake. “Cervical mucus is a little bit nuanced,” she says. “Sometimes [the changes are] very obvious and in other bodies, it’s not as obvious.”

Overall, this method works best for people with regular periods. If you have an irregular cycle (which means you frequently skip periods or get periods sooner than 21 days apart or more than 35 days apart), it’ll be harder to pinpoint exactly when you’re ovulating. This is particularly true if you have polycystic ovarian syndrome (PCOS). “You may be ovulating in a given cycle, or you may not be ovulating,” Dr. Blake explains. “It’s a little bit easier if your cycle is regular; then at least you know when you’re generally expecting your ovulation.” 

Certain things can also make it harder to track your cervical mucus changes, says Dr. Blake, which affects how effective this method is. For example, vaginal treatments for yeast infections or bacterial vaginosis can make it harder to detect your cervical mucus, she says. According to Planned Parenthood, other factors that might temporarily change your natural cervical mucus include vaginal sex, lube, breastfeeding, surgery, and sexually transmitted infections (STIs). 

Dr. Blake also doesn’t recommend trying to track your cervical mucus if you’re on hormonal birth control, because these medications typically stop ovulation and/or alter your cervical mucus to prevent pregnancy. 

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For all of these reasons, Dr. Blake typically recommends that her patients use cervical mucus tracking along with another method, like tracking your luteinizing hormone (LH) levels or taking your basal body temperature daily. These additional metrics can help “confirm whether your mucus follows that normal trajectory,” she says. Translation: You’ll have more data to confirm ovulation, which in turn will help you be more precise at timing sex.  

Another very, very important caveat: The cervical mucus method on its own is not the most effective way to prevent pregnancy, says Dr. Blake. Like other fertility awareness methods, it’s around 77 percent effective at preventing pregnancy — less than male condoms or even the pull-out method. And in this day and age, an unwanted pregnancy might not be something many people are willing to risk. If you are experienced at tracking your cycle and prefer this to other methods, Dr. Blake recommends using the aforementioned alternative methods in addition to cervical mucus tracking. (And when in doubt, use a backup method!)

How do I start tracking cervical mucus? 

You’ll need to have a notebook (or an app, like Clue or Ovia) to keep notes on your mucus and your cycle, plus any other fertility stats you record. If you’re recording stats by hand, format it as a chart that matches the date with the day of your cycle and includes any relevant information for that day. (You can use this one from Planned Parenthood as a template.) Start your chart on the first day of your period, which is also Day 1 of your cycle. 

woman using her phone to track cervical mucus

The best way to check your cervical mucus is to literally put your finger on it. Dr. Blake says with clean hands, insert your index finger inside your vagina and reach up toward your cervix. Pull it out slowly and then look at what residue is on your finger. Take notes of color, consistency, and texture, rubbing it between your finger and thumb to see if you can stretch it. You’re at peak fertility when the mucus is slippery, wet, and stretchy. Ideally, these observations would be paired with more qualitative measurements like your daily basal temperature or your current LH levels.

You should have at least one month of your cycle charted out before you start using this method for fertility to ensure that you understand your unique patterns. If you’re not noticing a difference in your cycle or having trouble tracking, it’s totally normal to feel discouraged or confused, says Dr. Blake. “​​It's a tough way to measure fertility and so that's why I really recommend that people have more than one method,” she says. Be sure to talk to your OB/GYN for more specific guidance.

*Dr. Rachel Blake is not affiliated with Fairhaven Health.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

Jessie Van Amburg is a health writer, reporter, and editor with 10 years of experience creating meaningful, compelling journalism in print and digital formats. Her work has been featured in TIME, Women's Health, Well+Good, and more.