Question: what does 2 cm dilated and 50 effaced mean?
Answer: When it is 50 percent effaced, it is about two centimeters long. When it is 100 percent effaced, it is "paper-thin." Effacement can happen over days before labor starts. Or, it can happen over hours as labor progresses. With a first labor, it can take quite a while for the cervix to completely efface.