Menstruation, periodic discharge from the vagina of blood, secretions, and disintegrating mucous membrane that had lined the uterus. 1  The biological significance of the process in humans can best be explained by reference to the reproductive function in other mammals.
Chlamydia is a common sexually transmitted disease (STD) caused by infection with Chlamydia trachomatis. It can cause cervicitis in women and urethritis and proctitis in both men and women.
Chlamydia Causes. Chlamydia is an infection caused by the bacterium Chlamydia trachomatis. The infection is transmitted in 2 ways: 1  From one person to another through sexual contact (oral, anal, or vaginal).2  From mother to child with passage of the child through the birth canal. From one person to another through sexual contact (oral, anal, or vaginal). 2  From mother to child with passage of the child through the birth canal. 3  Chlamydia can cause pneumonia or serious eye infections in a newborn, especially among children born to infected mothers in developing countries.