The cervix (also: neck of the womb, neck of the uterus) is a narrow fibro-muscular canal between the body of the uterus and the vagina. In gestation, it remains tightly shut to prevent premature birth of the fetus and to stop infectious agents from reaching the uterus through the vagina. In the first hours of labor, the cervix flattens and dilates to form a continuous canal between the uterus and vagina through which the fetus will pass. The dilation of the uterine mouth gives its name to the dilation stage of labor.