Cervix

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.