What is your mucus plug and what does it look like?

What is a mucus plug?

Your mucus plug is a thick clump of mucus in your cervical canal that acts as a protective barrier. The mucus plug starts forming around week 7 of pregnancy, and it helps stop bacteria and other sources of infection from getting into your uterus and harming your baby.

"Losing your mucus plug usually means your cervix is dilating (opening up) and becoming thinner and softer (effacing)," explains the U.S. Department of Health and Human Services' Office on Women's HealthOpens a new window. "Labor could start right away or may still be days away." 

The plug may also be dislodged by having sex, your baby dropping (when your baby's head drops into your pelvis), or during a pelvic exam in your provider's office. If your mucus plug comes out but labor doesn't start, your body will replace it with more mucus.

At some point after you lose your mucus plug, you may start to notice cramping, contractions, or other signs of early labor. With these signs, you may also see some thick, stringy, bloody discharge called bloody show. This is a combination of mucus and blood from vessels that have ruptured as the cervix begins to dilate and efface in preparation for active labor. Bloody show may be brownish, pink, or bright red and mixed with smaller amounts of mucus.

What does a mucus plug look like?

The mucus plug:

• May be transparent, off-white, a little pink or brown, or slightly blood-tinged
• Is thick, sticky, and stringy
• May come out gradually over several days (and be barely noticeable)
• May come out all at once in a big clump, about an inch or two in length
• Is relatively odorless

Is it my mucus plug or vaginal discharge?

Some women expel the entire mucus plug at once, according to the American College of Obstetricians and GynecologistsOpens a new window, while others lose it over time in what looks like an increase in vaginal discharge.

In fact, you might not notice when the mucus plug comes out because you may be used to seeing heavy vaginal discharge during pregnancy, caused by increased estrogen levels.

While discharge and your mucus plug can look pretty similar, here are some differences you may notice:

• If the discharge is pink or brown, it's likely your mucus plug. Healthy vaginal discharge is usually clear to milky white or light yellow.
• The mucus plug is usually thick, like jelly, and sticky. Vaginal discharge is usually thinner and more slippery than sticky.
• If the mucus comes out all at once in a big clump, it's your mucus plug (though again, it can come out over the course of days). Vaginal discharge is usually ongoing.

Sometimes vaginal discharge during pregnancy can signal a problem, such as a vaginal infection like bacterial vaginosis (BV) or a yeast infection. Call your provider if your discharge:

• Increases or changes in color, consistency, or amount
• Is green or gray, or smells bad
• Is frothy with an unpleasant odor
• Comes with itching or irritation of your vulva

"Sometimes small amounts of bright-red blood can be mixed with both discharge and your mucus plug," says Melissa Simon, M.DOpens a new window., vice-chair for research in the department of obstetrics and gynecology at Northwestern University Feinberg School of Medicine and a physician at Northwestern Medicine.

"This is very common, especially after intercourse or a vaginal exam. As long as it's a minimal amount, it's not concerning. But if you notice more than about two teaspoons of blood, call your provider immediately," says Dr. Simon.

When will I lose my mucus plug?

You'll lose your mucus plug sometime before you go into labor (usually after 37 weeks), or as labor is starting. This happens because as the cervix begins to open, the plug drops into the vagina. However, it could take hours, days, or even weeks for labor to actually begin after your mucus plug comes out.

What should I do after losing my mucus plug?

There's no need to do anything, though this might be a good time to make sure your hospital bag is packed and you're prepared for your baby's arrival.

While losing your mucus plug is one sign that your body's preparing for labor, it doesn't mean you need to head to the hospital or even call your provider. (Though, of course, if you have questions or are unsure, go ahead and call your doctor or midwife.)

To figure out whether it's time to go to the hospital or birth center, look for other signs of labor, such as regular contractions or your water breaking.

How long after losing my mucus plug does labor start?

There's no way to tell how long it'll take for labor to kick in after losing your mucus plug.  Losing your mucus plug can be a sign that labor is imminent. But it can also take several more days or even weeks for labor to begin.

"Every stage of pregnancy and labor is exciting to experience, as it brings you one step closer to meeting your baby," says Shannon Smith, M.D., an ob-gyn at Brigham Faulkner Ob/Gyn Associates in Boston. "However, when it comes to losing your mucus plug, don't get too excited."

Says Dr. Smith, "It's impossible to predict when labor will actually start – and for many women it's days or even weeks later. So be happy that your body is preparing for labor and things are happening, but understand that it doesn't predict when you'll kick into true, active labor."

If losing your mucus plug is accompanied by other early signs of labor, however, the birth of your baby is likely close.

Learn more:

• Brown discharge during pregnancy
• Your third trimester pregnancy guide and checklist
• What happens to your baby right after birth
• How to care for a newborn