As the name suggest, the transition phase takes place between the dilation and expulsion phases and is the most difficult part of the birth process. It mostly begins when the cervix has dilated to around 8 cm and ends when full dilation has been achieved.
The contractions during this phase are very painful and may follow on from each other without remittance. Frequently, the amniotic sac breaks at this time. Toward the end of the transition phase, there is usually a brief pause in the contractions before the last phase, known as the expulsion phase, commences.