Cervical dilation, the opening and thinning of the cervix, is a key process indicating the progression toward childbirth. While healthcare providers measure this, individuals can observe signs suggesting their body is preparing for labor.
Understanding Cervical Dilation
The cervix remains closed throughout most of pregnancy. As labor nears, it softens, thins (effacement), and gradually opens (dilation). Effacement is measured as a percentage, with 100% meaning the cervix is completely thinned. Dilation is measured in centimeters, from 0 cm (closed) to 10 cm (fully dilated), which is necessary for vaginal birth. Uterine contractions and the baby’s head descending into the pelvis influence these changes.
Key Signs of Dilation
Several observable signs indicate the cervix is beginning to dilate as the body prepares for labor.
Bloody show is vaginal discharge tinged with blood. It occurs as the cervix thins and opens, causing tiny blood vessels to tear and bleed, mixing with cervical mucus. The discharge may appear pink, brown, or red, and is generally not concerning unless bleeding is heavy.
The loss of the mucus plug, which seals the cervical opening during pregnancy, is another sign. As the cervix softens and dilates, this plug dislodges. It may be expelled as a clump or gradually as increased discharge. While it indicates cervical changes, labor is not necessarily immediate; it can happen days or weeks before contractions begin.
Changes in contractions are a more definitive sign. Unlike irregular Braxton Hicks, true labor contractions become progressively more regular, stronger, and longer. These contractions work to open and thin the cervix. Early labor contractions might feel like strong menstrual cramps or lower back pressure, lasting 30-45 seconds and occurring every 5-30 minutes. As labor progresses, they intensify, becoming more frequent and sustained.
Increased pressure in the pelvis or vagina can also signal cervical dilation. This sensation intensifies as the baby descends, pressing against the cervix. Some describe it as a strong urge to have a bowel movement, due to the baby’s head pressing on the rectum.
The rupture of membranes, or water breaking, is a clear sign labor has begun or is imminent. This involves the tearing of the amniotic sac, releasing fluid. While often a dramatic gush, it can also be a slow trickle. Only about 10% experience their water breaking before contractions start; most experience it during active labor.
Professional Confirmation and Guidance
Cervical dilation is professionally assessed through an internal vaginal examination by a healthcare provider. During this, the provider manually checks the cervix for its position, softness, effacement, and dilation in centimeters.
Self-checking cervical dilation is not recommended due to risks. Improper technique can introduce bacteria, potentially leading to infection. Without professional training, accurate assessment is difficult, leading to incorrect assumptions. Healthcare providers are trained to perform these assessments safely and interpret findings correctly.
Contact a healthcare provider when contractions become regular, lasting about 60 seconds and occurring every 3-5 minutes for at least an hour. Also contact them if your water breaks, regardless of contractions, or if there is significant vaginal bleeding or a decrease in fetal movement. These situations warrant immediate medical attention.
What Dilation Means for Labor Progression
Cervical dilation correlates with the stages of labor. The first stage, involving cervical changes, is divided into two main phases: latent and active.
The latent phase marks labor’s beginning, with the cervix slowly dilating from 0 to 3-6 centimeters. This is typically the longest phase, lasting hours or days, with mild, irregular contractions. The cervix softens and effaces in preparation for more rapid dilation.
The active phase follows, with more rapid cervical dilation, typically from 6 cm to 10 cm. Contractions become stronger, longer, and more frequent, making them harder to talk through. This phase signifies significant progress toward birth.
Full dilation, reaching 10 centimeters, marks the end of the first stage of labor and the beginning of the pushing stage. The cervix is completely open, allowing the baby to descend through the birth canal.