Stage 1: Early labor and active labor

The first stage of labor and birth happens when you begin to feel ongoing contractions. These contractions become stronger, and they happen more often as time goes on. They cause the cervix to open. This is called dilation. The contractions also soften, shorten and thin the cervix. That process is called effacement. It allows the baby to move into the birth canal.

The first stage of labor is the longest of the three stages. It's divided into two phases — early labor and active labor.