What You Need to Know About the Mucus Plug

Hazy on what the mucus plug is? You’re not alone. We’ve enlisted doctors to give us the unpretty yet necessary details.
ByKorin Miller
Sep 2017
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There’s a lot of new terminology to absorb when you’re pregnant, but you’ve probably heard of some of the language before, in passing. The term “mucus plug” is probably one of them—especially as you get close to your due date, when your OB may ask if you’ve lost yours yet. Before that happens, it’s smart to have a basic understanding of what the mucus plug is and what it does.

What Is a Mucus Plug?

The mucus plug is a thick plug of mucus and cells from the cervix that covers the opening of a woman’s uterus during pregnancy, says Charles Ascher-Walsh, MD, director of the division of gynecology at Mount Sinai Hospital in New York City. Your mucus plug starts to form when you become pregnant and the glands in your cervix secrete mucus, he says, but it doesn’t reach its full size until you’re about 12 weeks along. It usually stays in place throughout your pregnancy until you begin to dilate. It plays an important role, preventing bacteria from entering the uterus during pregnancy, says Maureen Whelihan, MD, an ob-gyn at the Center for Sexual Health & Education in Greenacres, Florida.
The mucus plug is distinctly different than “regular” discharge—it’s thicker and there’s more of it, says Michael Cackovic, MD, an ob-gyn at the Ohio State University Wexner Medical Center in Columbus. Normal vaginal discharge varies with the change in hormone levels during your regular cycle, but hormone levels during pregnancy are different and more constant, which creates a different type of mucus that turns into the mucus plug.

What Does a Mucus Plug Look Like?

As you can imagine, it’s mucus-y! It’s also thick and may be slightly bloody, Cackovic says. “The mucus plug color is usually white, yellowish, beige or brown, or any variant thereof,” he adds. “It can have a red or pink tinge associated with blood.” (Whelihan likens it to a “thick ball of snot.”)

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Since the mucus plug is designed to “plug” your cervix, it’s about the same size: approximately four centimeters long. It has the volume of about two tablespoons (in case you really want to know).

Losing Your Mucus Plug

Doctors and nurses usually ask whether a woman has lost her mucus plug when she’s in the later stages of her pregnancy—and there’s a reason for this. Losing your mucus plug is usually a sign that your body is preparing to go into labor (though a lost mucus plug isn’t a guarantee).

When do you lose your mucus plug?

Typically, you lose your mucus plug after 37 weeks. It’s possible to lose your mucus plug early, but that should prompt a call to your doctor. “Early loss may indicate preterm changes in the cervix and potential risk for preterm labor,” Whelihan says. “Also, loss of the mucus plug potentially exposes the pregnancy to infection.” If you think you lost your mucus plug early or aren’t sure, talk to your doctor. In fact, says Cackovic, “any increase in vaginal discharge [during pregnancy] should prompt a discussion and possible evaluation by an ob-gyn.”

What does it mean when your mucus plug falls out?

Losing your mucus plug “generally implies a change in the cervical opening size, either via dilation (widening) or effacement (softening and becoming thinner),” Whelihan says. This occurs because your hormones change at the end of your pregnancy—which is why losing your mucus plug often means labor is starting or your body is preparing for labor. That naturally prompts the question, “Can you dilate without losing your mucus plug?” The answer is no. “If the cervix dilates, the plug will always fall out,” Ascher-Walsh says.

How long after losing your mucus plug will labor start?

Unfortunately, losing your mucus plug isn’t a guarantee labor will start immediately after. “It could be hours, days or weeks” until a woman goes into labor after losing her plug, Cackovic says. “It’s not the reliable sign that some books make it out to be.”

How do I know if I lost my mucus plug?

While some women will spot the plug as soon as it comes out, it’s quite possible you might not realize you’ve lost your mucus plug at all. “Many women will never even pay attention to it,” Whelihan says.

Don’t stress if you’re getting close to your due date and you haven’t seen a mucus plug. “The loss of it has no real importance other than serving as a sign that labor may be soon,” Ascher-Walsh says.

How to make your mucus plug come out

If you’re past your due date, it’s understandable to want to do what you can to get labor going. It’s also natural to assume that making your mucus plug come out will speed up the process. Unfortunately, that’s not the case. While there are plenty of old wives’ tales about this, none have been proven, Ascher-Walsh says. Your doctor will have other ways to speed up the process, such as using Pitocin, if it becomes necessary. Otherwise, try to relax and let nature take its course.

Updated September 2017

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