Labor

the process of expulsion of the fetus and the placenta from the uterus

Description
The stages of labor include:
 * 1) first stage, beginning with the onset of uterine contractions through the period of dilation of the os uteri
 * 2) second stage, the period of expulsive effort, beginning with complete dilation of the cervix and ending with expulsion of the infant
 * 3) third or placental stage, the period beginning at the expulsion of the infant and ending with the completed expulsion of the placenta and membranes