What Is the Mucus Plug?

Illustration of mucus plug

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What Is the Mucus Plug?

In early pregnancy, the mucus plug forms, sealing the cervix (which sits between the vaginal canal and the uterus) with thick mucus to keep bacteria from entering the uterus. It protects the fetus from infection and helps prevent premature labor. Without the mucus plug, maintaining a pregnancy to term would be unlikely and, in some cases, impossible.

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Why It's Important

The mucus plug is formed in early pregnancy from secretions of cervical glands and has a thick, gelatinous consistency. Within this thick, sticky fluid are antibodies that can protect the growing fetus from many bacteria, viruses, and other disease-causing agents.

The mucus plug is affected by hormones, primarily progesterone (which thickens the mucus in early pregnancy) and estrogen (which thins the mucus in late pregnancy).

Shortly before labor begins, the mucus plug thins as the cervix gradually softens and dilates. The passing plug indicates that labor is nearing, regardless of the pregnancy stage. Therefore, if you pass the mucus plug during early or mid-pregnancy, you should contact a healthcare provider right away since it may be a sign of impending preterm birth.

What to Look For

When the mucus plug comes out, capillaries in the cervix may also rupture. This rupture sometimes results in passing visible streaks of blood along with some mucus, which is why some people refer to the loss of the mucus plug as the "bloody show." Though the events are related, they are different, and not everyone passes a mucus plug with blood. In fact, the appearance and texture of the mucus plug varies.

The mucus plug may appear creamy to yellowish-white; streaked with pink; pink, brown, or red-tinged; or even beige or brown. While mostly odorless like everyday vaginal discharge, the mucus plug is typically thicker and more jelly-like and may appear stringy or sticky.

It is impossible to predict precisely when the mucus plug will pass, as it varies from person to person and pregnancy to pregnancy. Most often, though, it occurs sometime before labor, generally after 37 weeks, at which point the amniotic fluid in the gestational sac offers ample protection for your baby right up until the time your water breaks. Other times, the mucus plug doesn't pass until after other labor symptoms have begun.

In some cases, you will notice the mucus plug in your underwear, in the toilet or on a piece of toilet paper when you use the bathroom, or even in the shower. In others, it comes out gradually over a few days, and you may not notice it at all. Some people experience a nagging pain in the lower abdomen similar to menstrual cramping, though this is less common.

If you happen to be aware of when your mucus plug comes out, or you notice bloody show, it could mean that labor is just a few hours away—or it could mean you still have weeks to go. 

Losing Your Mucus Plug Early

Sometimes people suspect that they've lost their mucus plug, when in fact, they're noticing typical vaginal discharge unrelated to the mucus plug. Many people experience increased vaginal discharge during pregnancy.

However, if you notice a mucousy discharge that does not seem usual for you make note of its appearance, texture, and amount, contact a healthcare provider for guidance. They can let you know what other signs to watch for and whether you should take further precautions.

Signs of Preterm Labor

Losing your mucus plug early may mean you're going into early labor. Symptoms of preterm labor include:

  • Bright red blood from your vagina
  • Contractions or cramps, more than five in one hour
  • Intense pelvic pressure
  • Low, dull backache
  • A sudden gush of clear, watery fluid from your vagina

Call a healthcare provider right away or seek emergency care if you experience any of these symptoms before 37 weeks.

A Word From Verywell

When the mucus plug passes, it is usually an exciting indication that labor is on its way. However, it is usually a good idea to call a doctor or midwife to get advice. Being in touch with a healthcare provider is especially important if you suspect you've lost the mucus plug before 37 weeks of pregnancy.

If passing the plug is accompanied by heavy bleeding or a deep red discharge, contact a doctor immediately, as these can signify potential complications.

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3 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Cleveland Clinic. Mucus plug.

  2. Critchfield AS, Yao G, Jaishankar A, et al. Cervical mucus properties stratify risk for preterm birth. PLoS ONE. 2013;8(8):e69528. doi:10.1371/journal.pone.0069528

  3. American College of Obstetricians and Gynecologists. Preterm labor and birth.