What Is The Mucus Plug?

In late pregnancy, a gelatinous flow often appears during urination. This can alarm a future mother! But this liquid indicates that birth is coming soon, and it is totally normal. 
What Is The Mucus Plug?

Last update: 05 September, 2018

As your due date approaches, your obstetrician will warn you about the expulsion of the mucus plug. This refers to a whitish or yellowish liquid that is expelled before giving birth. 

You may expel it hours, days, or weeks before birth, depending on your uterine dynamic.

The flow is dense, composed of water, proteins, enzymes, and immunoglobulins. It forms during the first weeks of pregnancy. As the name indicates, it acts as a “plug” for the uterine neck, separating the uterus from the vagina. It remains in the endocervical zone throughout most or all of the 40 weeks of gestation.

Sometimes, this gelatinous secretion can be accompanied by small amounts (threads) of blood. There is nothing to be worried about. The mucus plug was attached to the uterine neck for months, and it is possible for some blood vessels to burst when it detaches.

What is the Purpose of the Mucus Plug?

The mucus plug acts as a protective shield. It protects both the mother’s uterus and the baby. It keeps out bacteria and fungi, among other germs that can lead to multiple infections of the uterine cavity. 

For first-time mothers it is a new experience. You may expel it without noticing (while urinating) or you may notice spotting in your underwear.

It is not an abundant flow. However, when you notice that it is developing, avoid having sex or douching. Once it has been expelled, the uterine cavity becomes exposed to contaminating elements. 
What Is The Mucus Plug?

When is the Mucus Plug Expelled?

Usually the mucus plug is expelled during the final stage of pregnancy, when uterine activity begins. If your uterine dynamics are regular, it may happen during dilation.

If your contractions are irregular, the mucus may come out hours, days, or weeks before the baby is born.

If your mucus plug detaches before 34 weeks, consult your doctor immediately. Although it is not a signal of imminent labor, at that stage it can indicate premature birth or an incompetent cervix.

Both situations require prompt attention to prevent health problems or even losing the baby.
When faced with the threat of premature labor or an incompetent cervix, the specialist will do exhaustive tests, intervene, or indicate treatment to avoid delivery before week 37. If the delivery is urgent, work will need to be done for the baby’s lung maturation and complete development.

Your Doctor as a Partner in the Process 

How can you tell the difference between the mucus plug and the normal discharge during the final trimester? Could it be amniotic fluid? Spotting or hemorrhage? It is normal to have all these questions during your pregnancy, especially when it is your first child.

Expelling the barrier – sometimes without warning – is a natural physical process. There are no associated health risks. It is there to protect the fetus and bring the pregnancy to a happy conclusion. However, it is important to be informed about its characteristics and functions so you’ll know how to act in different circumstances.

During the 40 weeks of your pregnancy, your ob-gyn is not just your doctor; he or she is a partner in the process. Direct all your questions, concerns, and doubts to them.

What Is The Mucus Plug?

The Mucus Plug is Not Amniotic Fluid

It is important to differentiate between the mucus plug and amniotic fluidThe first is a dense, gelatinous flow. It isn’t very noticeable. It’s transparent, sometimes whitish, yellowish, or brown if it has traces of blood. The smell is sweet.

Amniotic fluid, on the other hand, is thin and smells slightly of chlorine. It is more similar to urine.

Both indicate that delivery is close. The rupture of the amniotic sac occurs after the mucus is eliminated, when the membranes compress and the child enters the birth canal.

Basically, amniotic fluid is colorless water, which can also be mixed with a small amount of blood. If you see very dark liquid you should see a doctor immediately.

Likewise, it is important to know the difference between expelling the mucus plug and a hemorrhage. It is normal to see threads of blood, but not large quantities.

If the bloody secretion is abundant and continues, tell your doctor immediately. hemorrhage can happen with or without pain. It signals a problem in the placenta or another reproductive organ. 


This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.