Effacement. Your cervix ripens.
Your cervix -- the lower, narrow end of the uterus that protrudes into the vagina -- softens as it's preparing for labor. This process, known as "ripening" or effacement, usually begins during the last month of your pregnancy. By the time the big day rolls around, your cervix will have stretched from around 1 inch in width to paper thinness. Your doctor or midwife may start checking for gradual effacement during your last two months of pregnancy with internal exams during your prenatal visits. Effacement is measured in percentages: Zero percent means no effacement; 100 percent means you're fully effaced.
Dilation. Your cervix opens.
As your baby's birthday approaches, your cervix begins to dilate, or open up. Dilation is checked during a pelvic exam and measured in centimeters (cms), from 0 cms (no dilation) to 10 cms (fully dilated). Typically, if you're 4 cms dilated, you're in the active stage of labor; if you're fully dilated, you're ready to start pushing.