The cervical mucus plug is a natural part of late pregnancy that often raises questions for expectant parents. Its loss can signal that the body is preparing for childbirth. Understanding what the mucus plug is and how it typically presents can offer reassurance during the final stages of pregnancy.
What the Mucus Plug Does
The mucus plug, medically known as the operculum, is a collection of thick, gelatinous cervical mucus that seals the opening of the cervix. Its primary physiological role is to act as a physical and chemical barrier between the vaginal environment and the uterus. This protective seal is formed early in pregnancy due to the influence of high progesterone levels, which cause cervical mucus to become dense and sticky.
This barrier is fortified with antimicrobial agents, including immunoglobulins and specific proteins, which help deter the passage of bacteria and other microorganisms. By blocking the cervical canal, the plug works to prevent ascending infections that could potentially affect the developing fetus.
How Much Mucus Plug Is Normal to See
The quantity of mucus plug observed varies widely, and often, it is not noticed at all. When expelled all at once, the plug is generally a squishy, jelly-like mass, approximating one to two tablespoons in volume.
The consistency is thick, sticky, and gelatinous, distinguishing it from normal vaginal discharge or amniotic fluid. Appearance can range from clear or off-white to yellowish, greenish, pink, or brown. The pink or brownish streaks are known as the “bloody show,” caused by the rupture of tiny blood vessels as the cervix begins to soften and dilate. If the plug comes out gradually, it may appear as an increase in thick, colored discharge over several days rather than a single distinct blob.
Timing of Mucus Plug Loss and Labor
Losing the mucus plug signals that the cervix is undergoing changes, but it does not mean labor is starting immediately. The plug is dislodged when the cervix begins to soften, thin (efface), and open (dilate) in preparation for birth. This cervical ripening process can occur slowly over time.
The plug may be expelled hours, days, or even a few weeks before the onset of active labor. Some individuals do not lose the plug until they are already in the established stages of labor. Because of this variability, losing the mucus plug alone is not a reliable predictor for the exact start time of contractions. Even if the plug is lost early, the body continues to produce cervical mucus, which still offers some level of protection to the fetus.
When to Contact a Healthcare Provider
The loss of the mucus plug after 37 weeks is considered a normal part of preparing for delivery. However, specific signs warrant contacting a healthcare provider immediately.
If the mucus plug is lost before 37 weeks of pregnancy, notify the provider, as this could indicate preterm labor. Medical advice should also be sought if the discharge contains a heavy amount of bright red blood, significantly more than just streaks of spotting. Heavy bleeding may signal a complication like placenta previa or placental abruption. Contact should also be made if there is a continuous gush or trickle of clear, watery fluid, which may indicate the rupture of the amniotic sac, or if the discharge has a foul odor or is green, suggesting an infection.