The cervix is part of a woman's reproductive system and is the lower, narrow part of the uterus that connects the uterus to the vagina.
The cervical canal is a passageway. Blood flows from the uterus through the cervical canal into the vagina during a woman's menstrual period. The cervix produces mucus that provides protection from infection. During ovulation the mucus assists the movement of sperm from the vagina into the uterus. When a woman is pregnant, the cervix is tightly closed to help keep the baby inside the uterus. During childbirth, the cervix opens to allow the baby to pass through the vagina.