Cervical Mucus 101


Have you ever been confused by vaginal discharge? Maybe you were worried you had an infection or something wasn’t right. Then, just like that, it’s gone again? 

If that sounds familiar, it is likely that nothing is wrong with you. In fact…Congratulations! You’ve just noticed the golden nectar of your fertility: cervical fluid. 

What is Cervical Fluid? 

Cervical fluid, often known as cervical mucus, is a hydrogel produced by the cervix. It contains mucus molecules, protein chains, minerals, and water – lots of it. When combined, this allows the vaginal fluids to form a unique electrolyte structure that changes throughout the menstrual cycle. During the first half of the cycle, rising estrogen levels cause the glands of the cervix to secrete fluid. The consistency and color of cervical fluid varies — from clear to watery, for example. When observed, it could look like raw egg white or sticky like glue stuck on your underwear.

This is all healthy, normal, and a key sign to unlocking your fertility. 
In a healthy cycle, you will start to see cervical fluid for an average of 5 days before ovulation.  The cervical mucus before ovulation is typically watery and often has a raw egg white type consistency at peak fertility. After ovulation occurs, your body will start to release the hormone progesterone, causing the mucus to thicken and form a “barrier” of sorts. From the outside, it will seem like the “water dried up”, in a sense, as discharge turns to white and lotion-like as it dissipates. The barrier created by the change in cervical mucus stops sperm (and any foreign substance) from getting through the uterus. Your cervix will stay closed off until your period arrives and the whole cycle starts again. Voila! Note that other fluid patterns are possible, particularly if you are experiencing changes in your cycle patterns due to stress, intake of hormonal birth control or other medications, hormonal issues such as PCOS, breastfeeding, or perimenopause.

Is cervical mucus really worth monitoring?

Did you know that ovulation only happens within one day in the entire cycle and, once the egg is released from the ovary, it only has 12 to 24 hours to be fertilized? With such a short ovulation period, it makes it all the more important to be monitoring the telltale signs of fertility.

Part of the reason we’re fertile for longer than 24 hours is because cervical fluid. Cervical fluid extends that small window of fertility to approximately 6 days of your cycle. With the help of cervical fluid, sperm can be kept alive for up to an incredible 5 days!

Contrary to popular belief, a woman is not always fertile. Outside of this 6 day fertile window, pregnancy is not possible. Cervical fluid plays a critical role in fertility and pregnancy because sperm cannot survive in the vagina unless cervical fluid is present. 

Art inspired by image from Justisse College International


Here’s 3 ways cervical fluid and sperm interact:

1. Cervical fluid makes the vagina a sperm-friendly place 

Naturally, the vagina is a hostile place for sperm due to its acidity (pH 4.5). Semen can only live in a milder pH between 7.2 and 8.4, which is a more basic environment. An acidic vaginal environment is helpful for killing harmful bacteria and preventing infections, but, it also prevents sperm from swimming up the reproductive tract. Once you enter your fertile window, the cervical fluid changes the pH to 7.9 which is more alkaline, or non-acidic, and actually helps keep the sperm alive.

2. Cervical fluid provides the necessary nutrients and energy for sperm to meet the egg 

 Cervical fluid has high water content, often exceeding 96% water.  With the help of cervical fluid and it’s high water content, often exceeding 96% water (Katz et al., 1997), the pathway to fertilize an egg is more accessible. Imagine going down the waterslide with no water flowing. Ouch. 

More amazingly, cervical fluid is rich with nutrients that the spermatozoa need to stay alive and have the energy to keep those tails swimming!

* PRO TIP * If you’re trying to conceive: sex on the day of maximal cervical fluid stretch (aka hydration) is most likely to be successful in timing intercourse for achieving pregnancy. This is even more accurate than using temperature shifts (which occur after ovulation), the calendar method or at times, ovulation prediction kits

3. Filters out abnormal sperm

When it comes to the 180 million sperm released in an ejaculate, it means survival of the fittest! 

Doesn’t this make sense? We don’t want just any weak sperm reaching that one precious egg.

Sperm with curved, irregular, or otherwise awkward swimming patterns who enter will find themselves pretty much stuck.

Most of the tens of millions of tiny swimmers don’t make it pass the uterus and into the fallopian tubes. It takes 5 to 68 minutes for the sperm to get to the point where they need to go to fertilize the egg. The journey is long and complex, many sperm die along the way, some sperm are mutated or abnormal (like have 2 heads and maybe abnormal genetic material).

Why don’t they make it? It’s not just the long journey but it is (you guessed it) the cervical fluid! Cervical fluid, in the fertile window, actually forms channels that the sperm have to navigate through.

These cervical fluid channels help to filter out the bad sperm (like the sperm with two heads and poor genetic content, for example). HOW AMAZING IS THAT?

Benefits of tracking your cervical fluid

According to one study, only 12.7% of people seeking fertility treatment can accurately identify their fertile window. With the knowledge you gain from tracking cervical fluid, you can proactively take charge of your reproductive health with less dependency on medical intervention. 

Cervical fluid can allow you to identify: 

  1. When you’ve entered your fertile window
  2. When you’ve exited it 
  3. Peak fertile days so that you can optimize your chances of conception.

Mapping the changes of your fertility’s key biomarker, the fertility nectar, can help give you insight into your hormonal balance, stress levels, reproductive health, and underlying medical conditions.


Written by Dr. Naomi Whittaker, MD NFPMC FCI

OB/Gyn NaProTechnology Fellow, Medical Advisor

Edited by Pear Poolvaraluk, kegg Marketing Lead

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“Hormone balance plays a huge role in fertility, and understanding what’s going on with your hormones doesn’t have to be such a mystery.

It’s actually way easier than most people realize.” 

— Amy Beckley, Proov Founder