The labor is divided into three stages.

1. Dilation of the mouth of the womb. This is indicated by cutting pains felt mostly in the back, contractions taking place in the womb only, and gradually growing more and more frequent until the neck of the womb is fully dilated.

2. Expulsion of the child, by means of stronger contractions in which the abdominal muscles contract, as well as the uterus.

3. The expulsion of the after-birth.

The average length of labor in women who have previously borne children is about six hours, the first four of which are occupied in the first stage, and the latter two in the second stage. The afterbirth is often expelled at once after the expulsion of the child, but is more often retained five to thirty minutes.

The first and second stages of labor are generally considerably prolonged. Some women, especially those who have broad hips and are well adapted to childbirth, pass through the process of labor in a much shorter space of time, in some cases not more than thirty minutes or an hour being occupied. In women who have not borne children before, especially those who are somewhat advanced in life, labor is often very greatly prolonged.

Various obstacles frequently arise to delay the process; such as, inactivity of the womb, rigidity of the neck of the womb or of the perinaeum, and contracted pelvis.