The cervix is the lower part of the uterus that opens into the vagina. It is part of a woman's reproductive system.

• During a woman's menstrual period, blood flows from her uterus through her cervix, down her vagina, and out of her body.
• During sex, the cervix makes mucus that helps sperm move up into the uterus.
• During pregnancy, the cervix is tightly closed to protect the baby. But later the cervix opens up so the baby can pass through the vagina during childbirth.