What does dilation refer to during labor?

Dilation during labor specifically refers to the opening of the cervix as the body prepares for childbirth. As labor progresses, the cervix must open to allow the baby to pass through the birth canal. This process is measured in centimeters, with full dilation being approximately 10 centimeters, which is necessary for the baby to be delivered. Thinning of the cervix, known as effacement, is a different process related to the cervix becoming softer and shorter, but it does not specifically refer to the opening, which is why dilation and effacement are often mentioned together but describe distinct phases of cervical change during labor. The position of the fetus and the length of labor are important aspects of the birthing process, but they are not directly related to the definition of dilation itself.