What Is a Mucus Plug?

what is a mucus plug during pregnancy
The mucus plug. It doesn’t have a pretty name and it is even ickier than it sounds, as made abundantly clear by its nickname, the “bloody show”. There’s a lot to learn during pregnancy — cool stuff, like the fact that babies can smell and grow fingernails in the womb, and weird stuff like they’re born without kneecaps. But, finding out about the mucus plug is one aspect of birth education that many moms find decidedly, um, gross. “Mine came out in the middle of sex two days before my son was born,” says Jen C., a new mom in Brooklyn, New York. “It was a total mess, and definitely lived up to the nickname.” Unpleasant as it may sound, you won’t mind so much once you know what the mucus plug actually does.

What is a mucus plug?

Kind of like a cork stopper, the mucus plug is a buildup of mucus that develops throughout your pregnancy in the endocervical canal. Its job is to protect your uterus and block the opening of the cervix to stop bacteria from getting in. It will come out near the end of your pregnancy. It might happen slowly over a couple of days, or it could dislodge in an instant. Either way, losing your mucus plug means your cervix is beginning to widen and your body is getting closer to going into labor.

What does it look like?

The mucus plug has the consistency of — you guessed it — mucus, so it’s thicker than the discharge you may be used to. “Some women will occasionally get an actual chunk or lump of mucus but most people just see a more copious, thicker discharge,” says April Sarvis, MD, an ob-gyn at Beaumont Hospital, in Bloomfield Hills, Michigan. Its texture can be stringy, sticky, or thick and varies in color from clearish, to light pink, or even red. 

Does losing my mucus plug signal the start of labor?

Not necessarily. “There is no absolute time frame correlating loss of plug and onset of labor,” says Adelaide G. Nardone, MD, FACOG, an ob-gyn at the Ryan Women and Children’s Center in New York City. “However, if the patient is having regular contractions at the time of her mucus release there is a higher likelihood she will deliver sooner than later.”

Should you call your healthcare provider when you lose your mucus plug?

Unless it’s watery enough that you think your water broke, hold off on the speed dial for now. Monitor how you are feeling as well as the rate and color of your discharge. If it seems excessive or bright red, it could be a sign of placenta previa, which your doctor will need to know about right away.

Are there any red flags to keep in mind?

Losing your mucus plug is totally normal, but you should definitely contact your medical provider if experience any of these symptoms at any time: 

  • Preterm contractions (before 37 weeks)
  • Bleeding (bright red compared to the possible dark tinge of your mucus plug)
  • Constant pain
  • Fever/chills
  • Mucopurulent discharge (pus mixed with the mucus)
  • Loss of amniotic fluid (aka your water breaking)

 Losing your mucus plug might be gross or you might not even notice, because here’s the thing: Increased vaginal discharge is already a pretty common pregnancy symptom. Either way, it’s a pretty good sign that you are nearing the end of your pregnancy!

Photo: Getty