The active stage is labor is between 4 cm and completely dilated. This is when the contractions are very strong and close together. Dilatation progresses at a much faster rate. The baby will need to be monitored more closely.
At about 4 cm most women enter the active stage of labor, see Dilation, Effacement, Station. This continues until the cervix is completely dilated and you begin to push. Some women enter the active stage before 4 cm and some after but 4 cm is the typical time that active labor begins.
During the active stage of labor the contractions can become quite intense and close together. This is the point when people typically get the epidural if that is what they choose. For women who decide to deliver without pain medicine, this is when the breathing techniques become necessary.
Because the contractions are stronger and closer together, the baby will need close monitoring, see Fetal Monitoring.. The monitoring helps to make sure the baby is handling the stress of labor. Sometimes internal monitors will be placed at this point.
There is often bleeding and mucous discharge, the water may break during this time as well. Labor can be messy and the nurses can provide clean towels and sheets to keep you dry and more comfortable during this process.
The cervix will dilate more quickly during the active stage. We expect at least a centimeter an hour but sometimes much more. The dilatation can sometimes come in spurts. You may go from 4-6 very quickly, be at six for a while, then suddenly become complete for example. Each women and indeed, each pregnancy, is different.