The first stage of labor is defined as the time of the onset of true labor until the cervix is completely dilated to 10 cm. This stage is also the longest and involves three phases.
Early labor begins when you go into labor until the cervix is dilated 3 cm.
Active labor occurs as the cervix continues to dilate from 3 cm to 7 cm.
Transition is the final phase of the first stage when the cervix continues to dilate fully to 10 cm. If your cervix has opened up to at least 2-3 centimetres dilated and the baby's head is well engaged (low down in your pelvis), your waters will be broken (see below under Artifical Rupture of Membranes). If it is not possible to break your waters a second Propess pessary may be inserted if appropriate.