Cervical dilation is the opening of the cervix, the muscular entrance to the uterus, and is the primary measurement used to track the progression of labor. For a baby to pass into the birth canal, this opening must widen significantly. Understanding this process and recognizing the body’s signals helps a person know when labor is truly underway and when to seek medical attention.
Understanding the Cervical Dilation Scale
The standardized measurement for cervical dilation ranges from zero to ten centimeters. Zero centimeters means the cervix is closed, which is the typical state before the onset of true labor. Labor is complete when the cervix reaches ten centimeters, meaning it is fully open and ready for the pushing stage of birth.
Dilation often occurs alongside effacement, which is the thinning of the cervix. Effacement is measured in percentages, from 0% (thick) to 100% (paper-thin). The cervix must both dilate and efface for the baby to pass through the birth canal successfully.
While some individuals may walk around for weeks at one or two centimeters of dilation, the active phase of labor generally begins around six centimeters. Contractions work to pull the cervix open and thin it out, allowing it to move from a closed, thick state to an open, fully effaced one.
The Professional Dilation Check
The only definitive way to measure cervical dilation is through a manual vaginal examination, also known as a digital check. A healthcare provider, such as an obstetrician, midwife, or labor and delivery nurse, performs this check using sterile, gloved fingers. They gently insert two fingers into the vagina to physically feel the opening of the cervix and estimate its width in centimeters.
The healthcare provider also uses this exam to assess the degree of effacement and the baby’s position in the pelvis. This procedure is the standard method for determining admission to the hospital and monitoring progress throughout labor.
Attempting to check dilation at home is strongly discouraged due to the anatomical difficulty and the significant risk of introducing bacteria. The cervix serves as a protective barrier against infection during pregnancy, and only trained medical personnel using sterile techniques should perform this assessment.
Observable Signs of Labor Progression
While a person cannot measure their own dilation, the body provides several indirect signs that suggest the cervix is changing and labor is progressing. A pattern of uterine contractions that become progressively longer, stronger, and closer together is the primary indicator. True labor contractions are typically felt in the lower back and abdomen, and they do not slow down or stop with rest or a change in activity.
Another common sign of cervical change is the “bloody show,” which is the loss of the mucus plug that sealed the cervix during pregnancy. This discharge is often sticky, jelly-like, and may be clear, pink, or tinged with blood. The passing of the mucus plug indicates that the cervix is beginning to soften and open, though labor may not start immediately.
The rupture of membranes, commonly called the “water breaking,” is a more definitive sign that often occurs during active labor. This may manifest as a sudden gush or a slow, continuous trickle of amniotic fluid. If the water breaks, it signals a direct pathway between the outside environment and the uterus, requiring professional assessment to monitor for potential complications.
Safety and Timing for Hospital Visits
The observable signs of labor progression should be used to determine when to contact a healthcare provider and head to the hospital or birthing center. For first-time parents, a widely used guideline is the 5-1-1 rule: contractions that are five minutes apart, lasting for one minute each, and continuing for at least one hour. This pattern typically signifies the transition from early to active labor.
If the water breaks, or if there is excessive vaginal bleeding, a person should call their provider immediately, regardless of the contraction pattern. Following the provider’s specific instructions based on individual circumstances is the safest course of action.