Chlamydia if left untreated can lead to pelvic inflammatory disease. I don't know how long it takes for PID to develop. Since chlamydia is generally symptom-less, as are a number of other sti's it is important to have FULL sti screening between sexual partners if possible.

Back to the question. PID (pelvic inflammatory disease) can cause permanent damage to the reproductive organs which can result in infertility.

Ask your doctor/gyno if there is a way to tell if you have developed PID. Then go from there.

Here is some information from the CDC on chlamydia, including information on PID.
http://www.cdc.gov/std/chlamydia/STDFact-C hlamydia.htm