How Cervical Mucus Can Tell You When You're Fertile

Cervical mucus may not seem like something worthy of your attention. But it has a surprisingly important role in fertility. Knowing the difference between fertile and non-fertile cervical mucus can help you prevent or achieve pregnancy. 

Hormones cause cervical mucus to undergo several changes throughout your menstrual cycle. These changes can help you determine where you are in your cycle, letting you know when you might be ovulating, which can be helpful if you are trying to either prevent or achieve pregnancy. 

What is cervical mucus, and what role does it play in conception? 

The glands of the cervix secrete fluid, which is what we know as cervical mucus. Depending on where you are in your cycle, as much as 98% of your cervical mucus is water. The mucus secreted around the time of ovulation contains the most water. It also contains amino acids, cholesterol, lipids, glucose, and mucin. 

Cervical mucus plays a crucial role in conception. Sperm cells must travel a great distance to reach an egg. Cervical mucus helps them survive this long journey and improves their momentum so they can reach the ovum. In addition, cervical mucus stops the sperm cells that appear to move abnormally.

Around the time of ovulation, the consistency of cervical mucus becomes thinner and more slippery. It also looks clear instead of milky white. This is fertile mucus. These changes enable sperm to travel through the uterus and down the fallopian tube, to reach the egg.

After ovulation occurs, your ovaries produce progesterone, which causes the mucus to become thicker and stickier. This kind of mucus creates a physical barrier so sperm and other microbes cannot pass. 

What does fertile cervical mucus look like?

Fertile cervical mucus is often described as looking like raw egg whites. It is clear, stretchy, watery, and usually abundant. 

Non-fertile mucus is thicker, less watery, and not stretchy. It tends to be white or yellow in color.

When is your cervical mucus most fertile?

Your cervical mucus is most fertile around ovulation, which usually occurs at mid-cycle. Studies have found that cervical mucus reaches peak fertility on the day of ovulation or 1 to 2 days before. 

Can you use your cervical mucus to track ovulation?

Yes! Once you know what to look for, you can accurately predict ovulation by tracking changes in your cervical mucus. Research suggests that 93% of women are able to distinguish between fertile and non-fertile mucus. 

The natural family planning method

You may have heard of the natural family planning method, otherwise known as fertility awareness. It uses the symptoms of ovulation to determine your fertile window. Once you know how to read your body’s signs, you will know when you are ovulating, which is when you are most likely to conceive. You can use this information to either prevent or achieve pregnancy. 

Fertility awareness-based methods can be up to 99% effective in preventing pregnancy when used correctly. Observing cervical mucus changes is 86% to 96% effective as a form of birth control.  

Your body gives you several different signals of ovulation:

• Changes in cervical mucus: As described above, the color and consistency of cervical mucus will change around the time of ovulation.

• Rise in temperature: Your basal body temperature refers to your lowest temperature when your body is at rest. It should be taken every day at the same time, right after waking up. After ovulation, your temperature will rise.

• Length of your cycles: Ovulation occurs about 14 days before your period. So if you track how long your cycles usually are, you can determine when you are most likely ovulating. 

Is there any way to increase the fertility of your cervical mucus?

There are multiple strategies and supplements some people believe improve cervical mucus fertility. Scientific data on this subject is limited, however, and the information that is available does not support any of these methods. 

Because cervical mucus is primarily water, staying hydrated might be helpful. Also, experts recommend a healthy lifestyle before getting pregnant. This includes limiting alcohol, quitting smoking, and eating healthy food. These healthy habits may improve fertility. 

Why trust our experts?

Written by:

Katherine Killoran, MD

Katherine Killoran, MD, is a board-certified gynecologist with more than 20 years of clinical experience.

Edited by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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