Around week 35 of your pregnancy, you may begin to experience cervical effacement. Cervical effacement describes the process of the cervix thinning -- which is different than dilation -- when the cervix opens to allow the baby to make her/his grand appearance. Women usually experience cervical effacement late in pregnancy, in response to the body's preparation for labor, as the baby's head begins to put pressure on the cervix.
When Effacement Begins
Cervical effacement can be different for every expectant mother. First-time mothers may not experience effacement at all until labor actually begins. On the other hand, women who have previously given birth may feel gradual cervical effacement over a period of several weeks. So, be aware that if cervical effacement begins several weeks before your expected due date, it does not necessarily guarantee labor is imminent. Labor patterns are unique, not only for each woman, but even for each pregnancy. The cervix must efface and dilate in order for the baby to pass out of the uterus and through the birth canal. Thus, cervical effacement is an essential part of birth.
Mucus Plug
A mucus plug is exactly what it sounds like -- a wad of mucus that keeps the cervix sealed during pregnancy. This promotes a healthy environment for the baby, keeping out certain pathogens and lowering the risk of premature birth. Cervical effacement loosens the mucus plug. You may begin noticing small clumps of stringy stuff covering your panties or coming out while you pee -- this will continue until eventually the plug falls completely out. This mucus may be tinged with blood, giving the process the moniker of the "bloody show." A little blood is completely normal, but if you’re experiencing much more than spotting, talk to your obstetrician immediately. The loss of the mucus plug often happens in close proximity to the beginning of labor, although it can also come out in response to certain activities, like intercourse. If this happens too early, it may begin to reform.
Measuring Effacement
Cervical effacement is measured in terms of percentages. For instance, a cervix that has not effaced at all is said to be 0% effaced, while a completely effaced cervix that has become very thin is closer to 100% effaced. Cervical effacement is actually a better predictor of impending labor than its counterpart, dilation.
Cervical Insufficiency
If the cervix effaces and/or dilates too early in the pregnancies, it can lead to preterm labor, premature birth, and even miscarriage. Women at risk for cervical insufficiency may begin having trans-vaginal ultrasounds in their second trimester in order for doctors to closely monitor changes to the cervix. If preterm labor becomes an issue, your doctor may begin treatments to give your preterm baby the best chance at survival.
How Often Should You Check?
As your due date nears and you begin to make more frequent trips to the obstetrician, your doctor or nurse practitioner will begin to keep an eye on how far your cervix has effaced. Because cervical effacement and dilation are not always accurate predictors of labor, some practitioners do choose to skip cervical effacement exams. The release of cervical mucus flushes bacteria out of the birth canal. Though practitioners wear gloves during cervical exams, each cervical exam has the possibility of introducing bacteria into the uterus, particularly as the mucus plug begins to disintegrate. For this reason, many practitioners limit their cervical exams to times when they will be most beneficial. If you’re concerned about the frequency of your cervical exams, talk to your health care team.
