Effacement While you are pregnant, your cervix is usually around 2 to 3 cm long. In late pregnancy or early labor, Braxton Hicks' practice contractions start to shorten the cervix, a process known as effacement. Most women have a cervix that has shortened to 1 cm during the very early stages of labor. This is also referred to as 50 percent effaced. As the cervix continues to shorten, the cervix is gradually drawn up by the uterus, and by the time it is 100 percent effaced, the cervix will have started to open.

Dilation Once your cervix is stretched and softened, it begins to open, or dilate, so that your baby can pass through into the vagina to be born. Regular contractions cause the cervix to dilate, and in first labors the cervix dilates at an average of 1 cm per hour; this rate is often faster for subsequent labors. Here, at 2 cm dilation, the cervix has shortened and is beginning to open. Contractions may still be irregular.

Dilation -- 6 cm At 6 cm dilation, you are in active labor. Your contractions will be more frequent, regular, and stronger.

Dilation -- 10 cm At 10 cm dilation, you are fully dilated . Contractions may be almost continuous and you are nearly ready to start pushing your baby out.