When a woman is 2 centimeters dilated, it is considered early labor and can still take many hours to advance to active labor once contractions set in, according to Mayo Clinic. This phase of labor is unpredictable, taking up to 12 hours to advance to active labor for first-time mothers.
During early labor, vaginal discharge may be tinged with brown or red blood, signaling the loss of the mucus plug that protects the uterus during pregnancy, explains Mayo Clinic. Contractions can also begin at this time and become more and more regular, lasting for about 30 to 90 seconds. During this time, a woman can continue to take part in daily activities until the contractions become closer together and are more painful.
Once active labor begins, contractions become closer together and the cervix dilates to 10 centimeters, giving way to the baby to make its passage, notes Mayo Clinic. Active labor begins at 4 centimeters of dilation. Active labor can take up to eight hours for first-time mothers, or it can be much shorter for women who have had a previous vaginal delivery. Once the cervix is dilated to 10 centimeters, pushing begins and the baby is delivered, followed by the placenta.