Chlamydia is a common sexually transmitted disease (STD) caused by the bacteria Chlamydia trachomatis. If left untreated, the bacteria can damage a woman's reproductive organs. It can scar tissue in the fallopian tubes, which may cause infertility (or inability to become pregnant in later years). It is transmitted during unprotected vaginal, anal or oral sex. It can also be passed from an infected mother to her newborn during vaginal childbirth.

Chlamydia is known as a "silent" disease because most women and 50% of men who are infected have no symptoms. The infection is frequently not diagnosed or treated until damage is already severe. That is why it is important to get checked if you've ever had unprotected sex. Just because you look and feel healthy, doesn't mean you're not infected.

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