Cervical effacement and dilation

Illustration of cervical effacement and dilation 
During the first stage of labor, the cervix opens (dilates) and thins out (effaces) to allow the baby to move into the birth canal. In figures A and B, the cervix is tightly closed. In figure C, the cervix is 60 percent effaced and 1 to 2 cm dilated. In figure D, the cervix is 90 percent effaced and 4 to 5 cm dilated. The cervix must be 100 percent effaced and 10 centimeters dilated before a vaginal delivery.
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