When you’re in labor, your healthcare provider will use the diameter of the opening of your cervix as an indicator of how far along you are. The opening becomes wider as a result of repeated contractions and pressure from Baby’s head (or bottom if it is in a breech position).
Dilation during pregnancy
As your cervix dilates during pregnancy, a mucus plug forms to seal the opening. In the third trimester, your cervix may dilate up to 3 cm, and the mucus plug could be released in one piece or as a thick discharge. You might not see this until right before your water breaks. Dislodging of the mucus plug is caused by a combination of dilating and stretching or thinning of the cervix in preparation for labor. You may feel menstrual-like cramps along with this dilation, which become more intense during labor.
Dilation during labor
Dilation is important for giving Baby an easier way to get out. Dilating to completion (10 cm) could take anywhere from a few hours to a few days, and there’s no way to predict how long you’ll be in labor.
If you are two weeks past your due date or have no contractions after your water breaks, your healthcare provider may recommend inducing labor. Other motivations for inducing labor include health risks posed to you or Baby, such as an infection in your uterus, deterioration of the placenta, or insufficient amniotic fluid surrounding Baby. Inducing dilation of your cervix could be done manually, by separating the amniotic sac from the cervix with a gloved finger or balloon-tipped catheter, or with medication.
Reviewed by Dr. Jamie Lo
- Mayo Clinic Staff. “Fetal development: The third trimester.” Mayo Clinic. Mayo Clinic, 7/11/2014. Web.
- “Cervical effacement and dilation.” Mayo Clinic. Mayo Clinic, n.d. Web.