The body undergoes transformations during the final stages of pregnancy as it prepares for childbirth. These changes are part of a natural process that gradually ready the uterus and cervix for the baby’s arrival. Understanding physical developments can help you feel more informed and at ease.
Understanding Cervical Changes
Cervical effacement refers to the process where the cervix, the lower part of the uterus, thins out and shortens. This thinning and softening prepare for vaginal delivery. Normally, the cervix is about 3 to 4 centimeters long and relatively thick. As effacement occurs, it becomes shorter and thinner, similar to how a turtleneck sweater neck might stretch and thin.
Healthcare providers measure effacement in percentages, from 0% (no thinning) to 100% (completely thinned). When 50% effaced, the cervix has thinned to half its original thickness or length, typically around 2 centimeters. This change is influenced by pressure from the baby’s head descending into the pelvis and uterine contractions.
How Long Effacement Can Last
There is no definitive timeline for how long someone can remain 50% effaced before labor begins. Duration varies significantly among individuals and across pregnancies. Some individuals may be partially effaced for several weeks without going into active labor.
For first pregnancies, effacement often progresses before significant cervical dilation. In subsequent pregnancies, the cervix might dilate and efface concurrently or dilate first. It is also possible for the cervix to remain 0% effaced until labor begins. Many do not experience noticeable symptoms as their cervix effaces, making regular healthcare provider checks important for monitoring progress.
Next Steps to Labor
As effacement progresses, the cervix also begins to dilate, which means it opens. Dilation is measured in centimeters, from 0 to 10 centimeters, with 10 centimeters indicating full dilation. Effacement and dilation typically work together, though one may occur more rapidly.
Other signs indicate labor is progressing:
Contractions become more regular, increasing in intensity, duration, and frequency.
The loss of the mucus plug, sometimes called a “show,” appearing as a thick, often blood-tinged discharge. This can happen days or even weeks before labor starts.
The baby may “drop” or descend further into the pelvis, leading to less pressure in the upper abdomen and more in the pelvis.
“Water breaking,” or the rupture of the amniotic sac, indicates labor is either underway or will begin soon.
When to Contact Your Provider
Contact your healthcare provider if you are 50% effaced and experience certain symptoms. Call if you have regular, strong contractions that become increasingly frequent and last approximately 60 seconds each, especially if they occur every five minutes for at least an hour. Immediate contact is also necessary if your water breaks, particularly if the fluid is not clear, or if this occurs before 37 weeks of pregnancy.
Also contact your provider for heavy vaginal bleeding (more than just spotting), a significant decrease in your baby’s movement, or severe abdominal pain that does not subside. Contact your healthcare provider if something “doesn’t feel right.”