Cervical dilation is a natural process as the body prepares for childbirth. This gradual opening of the cervix is a key indicator of labor progression.
Understanding Cervical Dilation
Cervical dilation refers to the widening of the cervix, which connects the uterus to the vagina. This opening is measured in centimeters, from 0 cm when fully closed to 10 cm for complete dilation. Alongside dilation, cervical effacement occurs, where the cervix thins and shortens. Effacement is measured as a percentage, from 0% to 100%. Both processes prepare the cervix for the baby’s passage.
When Dilation Typically Starts
The timing of initial cervical dilation varies significantly from person to person. Some individuals may experience slight dilation, such as 1 to 3 centimeters, weeks before the onset of labor. This early opening is a normal part of the body’s preparation and does not necessarily mean labor is imminent. For others, particularly those giving birth for the first time, dilation may only begin once labor contractions have actively started. Healthcare providers may begin checking for dilation during routine visits around 36 to 37 weeks of pregnancy to monitor these preparatory changes.
Progression During Labor
Once active labor begins, cervical dilation typically progresses through distinct phases. The latent phase, or early labor, sees the cervix dilate from 0 to about 6 centimeters. Contractions during this phase are generally mild and may be irregular, gradually becoming stronger and more frequent.
Following this, active labor is characterized by more rapid dilation, moving from 6 to 10 centimeters. Contractions in active labor become more intense, regular, and closer together, often lasting 45 to 90 seconds. The final stretch, known as the transition phase, involves dilation from 8 to 10 centimeters, often marked by the most intense contractions and a strong urge to push.
Factors Influencing Dilation and When to Seek Medical Advice
Several factors can influence the rate and timing of cervical dilation. Individuals who have given birth before often experience faster dilation compared to those in their first pregnancy. The baby’s position, specifically if the head is down and applying pressure to the cervix, can also facilitate dilation. Strong and regular uterine contractions are also necessary for the cervix to open effectively.
While some early dilation is normal in late pregnancy, it is important to contact a healthcare provider if there are concerns about labor progression or other symptoms. Signs such as consistent, strong contractions that become closer together, the breaking of water (rupture of membranes), or any significant vaginal bleeding warrant immediate medical attention. Feeling the baby move lower into the pelvis, known as lightening, or experiencing increased vaginal discharge or a “bloody show” (mucus tinged with blood) can also indicate that labor is approaching, prompting a conversation with a healthcare provider.