Font Size   Topic Overview  What is chlamydia?  Chlamydia (say
"kluh-MID-ee-uh") is an infection spread through sexual contact.
This infection infects the urethra in men. In women, it infects
the urethra and the cervix and can spread to the reproductive
organsClick here to see an illustration.. It is one of the most
common sexually transmitted infections (STIs).  Chlamydia does
not cause problems if you treat it right away. But left
untreated, it can lead to serious problems, especially for
women:    • If it spreads, it can cause pelvic inflammatory
disease. This serious infection can make it hard or impossible
for a woman to get pregnant.   • Pregnant women who have
chlamydia often pass it to their babies at birth. If the
infection gets in a baby's eyes, it can cause blindness. They
can also have other problems, like pneumonia. Pneumonia can be
deadly in a newborn.   • Having chlamydia makes a person more
likely to get HIV from someone who is infected with HIV. HIV is
the virus that causes AIDS.  What causes