This is one of those gross-sounding but totally normal parts of pregnancy: the mucus plug. As the name implies, it's basically a big blob of mucus blocking the top of your cervix to keep your baby safe from germs from the outside world.
"The mucus plug seals the opening of the cervix during pregnancy, similar to a cork, forming a protective barrier along with the amniotic sac," says Clara Ward, M.D., a maternal-fetal medicine physician with McGovern Medical School at UTHealth/UT Physicians in Houston, Texas. "Antibodies present in the mucus neutralize bacteria, viruses, and other causes of disease." The hormone progesterone, she says, makes the mucus nice and thick.
As you near the end of pregnancy and your body starts getting ready to push everything out during labor, your mucus plug is the first thing to go. "In the last days to weeks of pregnancy the mucus plug is lost as the cervix starts to soften, shorten, and even dilate in the process of preparing the cervix for labor," says Amy VanBlaricom, M.D., medical director of operations at Ob Hospitalist Group, a nationwide ob-gyn hospitalist employer. "These preparations of the cervix essentially push out the plug of mucus that has accumulated there."
For some women, the mucus plug comes out all at once. "It looks like a stretchy glob, similar to what may come out of your nose," says Dr. Ward. "It can be clear, yellowish white, beige, brown or pink, or tinged with red or brown streaks of blood."
For other women, it comes out gradually, and you may not even know it's happened; or you may only see it when wiping after going to the bathroom. "Not all women notice they have lost it, as it can blend in with the other increased secretions that lubricate the vagina in the late stages of pregnancy," says Dr. VanBlaricom, who is based in Seattle, Washington.
If you do notice it happening, does this mean labor is on its way? Yes, eventually, but don't rush out of the house just yet: You could be waiting for weeks.
"Losing the mucus plug can occur days to even weeks before labor begins and is not predictive of when that will start," says Dr. VanBlaricom. That's why you also don't need to worry about not noticing it coming out.
And unless your water has broken, your baby is still protected even after the mucus plug falls out. "If you lose your mucus plug but don't go into labor for a while it doesn't mean that baby is in danger of infection," says Dr. Ward. "Your cervix continues to produce mucus to replenish what is lost, and the amniotic fluid has many immunological agents that continue to protect baby against infection."
Losing the mucus plug sometimes gets confused with the unpleasantly-named "bloody show," which sounds like a horror movie but is also a totally normal early labor sign. "Bloody show refers to the passage of blood at the end of pregnancy; the cervix has many blood vessels that may bleed easily once the cervix starts to dilate," says Dr. Ward. "Bloody show can occur in conjunction with losing the mucus plug, but not always. It can sometimes mean that labor is closer, compared to if you are only seeing mucus."
Bloody show may also be more blood than mucus, explains Dr. VanBlaricom, and even have a flow like a period. And because bloody show can represent more advanced changes in your cervix, she recommends calling your doctor, especially if you are preterm or have other pregnancy-related complications.
Once you lose your mucus plug (if you notice it happening), you might want to look out for some other early signs of labor. "Other signs include 'lightening,' or the sensation that the baby has 'dropped,'" says Dr. Ward. "While this may result in more pressure in the pelvic region, breathing may be easier."
It's possible to also feel more cramping, back pain or even contractions. Changes in your activity level, including tiredness or nesting, may also occur, as well as a feeling of looser joints. "Your doctor may also let you know that your cervix has started to dilate or thin out," adds Dr. Ward.
Despite possible symptoms, both doctors agree there's usually no reason to worry when you lose your mucus plug near the end of pregnancy, especially when no other changes have occurred. "If you are full term—more than 37 weeks—there is probably no need to call your doctor unless you are bleeding heavily, contracting regularly, the mucus is particularly foul-smelling or you are concerned that you may have broken your water," says Dr. Ward. But "although there is likely no need for concern, if you are ever uncertain as to whether or not to call your doctor, you should always call to be on the safe side."